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Leave a comment Posted on May 10, 2018 May 10, 2018 Forensics, ULTRs
Forensic Failures Described via Law in Focus @ CSIDDS |
Faulty Forensics: Explained
By Jessica Brand
(West Midlands Police / Flickr [CC])
In our Explainer series, Fair Punishment Project lawyers help unpack some of the most complicated issues in the criminal justice system. We break down the problems behind the headlines — like bail, civil asset forfeiture, or the Brady doctrine — so that everyone can understand them. Wherever possible, we try to utilize the stories of those affected by the criminal justice system to show how these laws and principles should work, and how they often fail. We will update our Explainers quarterly to keep them current.
In 1992, three homemade bombs exploded in seemingly random locations around Colorado. When police later learned that sometime after the bombs went off, Jimmy Genrich had requested a copy of The Anarchist Cookbook from a bookstore, he became their top suspect. In a search of his house, they found no gunpowder or bomb-making materials, just some common household tools — pliers and wire cutters. They then sent those tools to their lab to see if they made markings or toolmarks similar to those found on the bombs.
At trial, forensic examiner John O'Neil matched the tools to all three bombs and, incredibly, to an earlier bomb from 1989 that analysts believed the same person had made — a bomb Genrich could not have made because he had an ironclad alibi. No research existed showing that tools such as wire cutters or pliers could leave unique markings, nor did studies show that examiners such as O'Neil could accurately match markings left by a known tool to those found in crime scene evidence. And yet O'Neil told the jury it was no problem, and that the marks "matched … to the exclusion of any other tool" in the world. Based on little other evidence, the jury convicted Genrich.
Twenty-five years later, the Innocence Project is challenging Genrich's conviction and the scientific basis of this type of toolmark testimony, calling it "indefensible." [Meehan Crist and Tim Requarth / The Nation]
There are literally hundreds of cases like this, where faulty forensic testimony has led to a wrongful conviction. And yet as scientists have questioned the reliability and validity of "pattern-matching" evidence — such as fingerprints, bite marks, and hair — prosecutors are digging in their heels and continuing to rely on it. In this explainer, we explore the state of pattern-matching evidence in criminal trials.
What is pattern-matching evidence?
In a pattern-matching, or "feature-comparison," field of study, an examiner evaluates characteristics visible on evidence found at the crime scene — e.g., a fingerprint, a marking on a fired bullet ("toolmark"), handwriting on a note — and compares those features to a sample collected from a suspect. If the characteristics, or patterns, look the same, the examiner declares a match. [Jennifer Friedman & Jessica Brand / Santa Clara Law Review]
Typical pattern-matching fields include the analysis of latent fingerprints, microscopic hair, shoe prints and footwear, bite marks, firearms, and handwriting. ["A Path Forward" / National Academy of Sciences"] Examiners in almost every pattern-matching field follow a method of analysis called "ACE-V" (Analyze a sample, Compare, Evaluate — Verify). [Jamie Walvisch / Phys.org]
Here are two common types of pattern-matching evidence:
Fingerprints: Fingerprint analysts try to match a print found at the crime scene (a "latent" print) to a suspect's print. They look at features on the latent print — the way ridges start, stop, and flow, for example — and note those they believe are "significant." Analysts then compare those features to ones identified on the suspect print and determine whether there is sufficient similarity between the two. (Notably, some analysts will deviate from this method and look at the latent print alongside the suspect's print before deciding which characteristics are important.) [President's Council of Advisors on Science and Technology]
Firearms: Firearm examiners try to determine if shell casings or bullets found at a crime scene are fired from a particular gun. They examine the collected bullets through a microscope, mark down characteristics, and compare these to characteristics on bullets test-fired from a known gun. If there is sufficient similarity, they declare a match. ["A Path Forward" / National Academy of Sciences"]
What's wrong with pattern-matching evidence?
There are a number of reasons pattern-matching evidence is deeply flawed, experts have found. Here are just a few:
These conclusions are based on widely held, but unproven, assumptions.
The idea that handwriting, fingerprints, shoeprints, hair, or even markings left by a particular gun, are unique is fundamental to forensic science. The finding of a conclusive match, between two fingerprints for example, is known as "individualization." [Kelly Servick / Science Mag]
However, despite this common assumption, examiners actually have no credible evidence or proof that hair, bullet markings, or things like partial fingerprints are unique — in any of these pattern matching fields.
In February 2018, The Nation conducted a comprehensive study of forensic pattern-matching analysis (referenced earlier in this explainer, in relation to Jimmy Genrich). The study revealed "a startling lack of scientific support for forensic pattern-matching techniques." Disturbingly, the authors also described "a legal system that failed to separate nonsense from science in capital cases; and consensus among prosecutors all the way up to the attorney general that scientifically dubious forensic techniques should not only be protected, but expanded." [Meehan Crist and Tim Requarth / The Nation]
Similarly, no studies show that one person's bite mark is unique and therefore different from everyone else's bite mark in the world. [Radley Balko / Washington Post] No studies show that all markings left on bullets by guns are unique. [Stephen Cooper / HuffPost] And no studies show that one person's fingerprints — unless perhaps a completely perfect, fully rolled print — are completely different than everyone else's fingerprints. It's just assumed. [Sarah Knapton / The Telegraph]
Examiners often don't actually know whether certain features they rely upon to declare a "match" are unique or even rare.
On any given Air Jordan sneaker, there are a certain number of shared characteristics: a swoosh mark, a tread put into the soles. That may also be true of handwriting. Many of us were taught to write cursive by tracing over letters, after all, so it stands to reason that some of us may write in similar ways. But examiners do not know how rare certain features are, like a high arch in a cursive "r" or crossing one's sevens. They therefore can't tell you how important, or discriminating, it is when they see shared characteristics between handwriting samples. The same may be true of characteristics on fingerprints, marks left by teeth, and the like. [Jonathan Jones / Frontline]
There are no objective standards to guide how examiners reach their conclusions.
How many characteristics must be shared before an examiner can definitively declare "a match"? It is entirely up to the discretion of the individual examiner, based on what the examiner usually chalks up to "training and experience." Think Goldilocks. Once she determines the number that is "just right," she can pick. "In some ways, the process is no more complicated than a child's picture-matching game," wrote the authors of one recent article. [Liliana Segura & Jordan Smith / The Intercept] This is true for every pattern-matching field — it's almost entirely subjective. ["A Path Forward" / National Academy of Sciences"]
Unsurprisingly, this can lead to inconsistent and incompatible conclusions.
In Davenport, Iowa, police searching a murder crime scene found a fingerprint on a blood-soaked cigarette box. That print formed the evidence against 29-year-old Chad Enderle. At trial, prosecutors pointed to seven points of similarity between the crime scene print and Enderle's print to declare a match. But was that enough? Several experts hired by the newspaper to cover the case said they could not draw any conclusions about whether it matched Enderle. But the defense lawyer didn't call an expert and the jury convicted Enderle. [Susan Du, Stephanie Haines, Gideon Resnick & Tori Simkovic / The Quad-City Times]
Why faulty forensics persist
Despite countless errors like these, experts continue to use these flawed methods and prosecutors still rely on their results. Here's why:
Experts are often overconfident in their abilities to declare a match.
These fields have not established an "error rate" — an estimate of how often examiners erroneously declare a "match," or how often they find something inconclusive or a non-match when the items are from the same source. Even if your hair or fingerprints are "unique," if experts can't accurately declare a match, that matters. [Brandon L. Garrett / The Baffler]
Analysts nonetheless give very confident-sounding conclusions — and juries often believe them wholesale. "To a reasonable degree of scientific certainty" — that's what analysts usually say when they declare a match, and it sounds good. But it actually has no real meaning. As John Oliver explained on his HBO show: "It's one of those terms like basic or trill that has no commonly understood definition." [John Oliver / Last Week Tonight] Yet, in trial after trial, jurors find these questionable conclusions extremely persuasive. [Radley Balko / Washington Post]
Why did jurors wrongfully convict Santae Tribble of murdering a Washington, D.C., taxi driver, despite his rock-solid alibi supported by witness testimony? "The main evidence was the hair in the stocking cap," a juror told reporters. "That's what the jury based everything on." [Henry Gass / Christian Science Monitor]
But it was someone else's hair. Twenty-eight years later, after Tribble had served his entire sentence, DNA evidence excluded him as the source of the hair. Incredibly, DNA analysis established that one of the crime scene hairs, initially identified by an examiner as a human hair, belonged to a dog. [Spencer S. Hsu / Washington Post]
Labs are not independent — and that can lead to biased decision-making.
Crime labs are often embedded in police departments, with the head of the lab reporting to the head of the police department. ["A Path Forward" / National Academy of Sciences] In some places, prosecutors write lab workers' performance reviews. [Radley Balko / HuffPost] This gives lab workers an incentive to produce results favorable to the government. Research has also shown that lab technicians can be influenced by details of the case and what they expect to find, a phenomenon known as "cognitive bias." [Sue Russell / Pacific Standard]
Lab workers may also have a financial motive. According to a 2013 study, many crime labs across the country received money for each conviction they helped obtain. At the time, statutes in Florida and North Carolina provided remuneration only "upon conviction"; Alabama, Arizona, California, Missouri, Wisconsin, Tennessee, New Mexico, Kentucky, New Jersey, and Virginia had similar fee-based systems. [Jordan Michael Smith / Business Insider]
In North Carolina, a state-run crime lab produced a training manual that instructed analysts to consider defendants and their attorneys as enemies and warned of "defense whores" — experts hired by defense attorneys. [Radley Balko / Reason]
Courts are complicit
Despite its flaws, judges regularly allow prosecutors to admit forensic evidence. In place of hearings, many take "judicial notice" of the field's reliability, accepting as fact that the field is accurate without requiring the government to prove it. As Radley Balko from the Washington Post writes: "Judges continue to allow practitioners of these other fields to testify even afterthe scientific community has discredited them, and even after DNA testing has exonerated people who were convicted, because practitioners from those fields told jurors that the defendant and only the defendant could have committed the crime." [Radley Balko / Washington Post]
In Blair County, Pennsylvania, in 2017, Judge Jolene G. Kopriva ruled that prosecutors could present bite mark testimony in a murder trial. Kopriva didn't even hold an evidentiary hearing to examine whether it's a reliable science, notwithstanding the mounting criticism of the field. Why? Because courts have always admitted it. [Kay Stephens / Altoona Mirror]
Not surprisingly, flawed evidence leads to flawed outcomes. According to the Innocence Project, faulty forensic testimony has contributed to 46 percent of all wrongful convictions in cases with subsequent DNA exonerations. [Innocence Project] Similarly, UVA Law Professor Brandon Garrett examined legal documents and trial transcripts for the first 250 DNA exonerees, and discovered that more than half had cases tainted by "invalid, unreliable, concealed, or erroneous forensic evidence." [Beth Schwartzapfel / Newsweek]
Hair analysis
In 2015, the FBI admitted that its own examiners presented flawed microscopic hair comparison testimony in over 95 percent of cases over a two-decade span. Thirty-three people had received the death penalty in those cases, and nine were executed. [Pema Levy / Mother Jones] Kirk Odom, for example, was wrongfully imprisoned for 22 years because of hair evidence. Convicted of a 1981 rape and robbery, he served his entire term in prison before DNA evidence exonerated him in 2012. [Spencer S. Hsu / Washington Post]
In 1985, in Springfield, Massachusetts, testimony from a hair matching "expert" put George Perrot in prison — where he stayed for 30 years — for a rape he did not commit. The 78-year-old victim said Perrot was not the assailant, because, unlike the rapist, he had a beard. Nonetheless, the prosecution moved forward on the basis of a single hair found at the scene that the examiner claimed could only match Perrot. Three decades later, a court reversed the conviction after finding no scientific basis for a claim that a specific person is the only possible source of a hair. Prosecutors have dropped the charges. [Danny McDonald / Boston Globe]
In 1982, police in Nampa, Idaho, charged Charles Fain with the rape and murder of a 9-year-old girl. The government claimed Fain's hair matched hair discovered at the crime scene. A jury convicted him and sentenced him to death. DNA testing later exonerated him, and, in 2001, after he'd spent two decades in prison, a judge overturned his conviction. [Raymond Bonner / New York Times]
Bite mark analysis
In 1999, 26 members of the American Board of Forensic Odontologyparticipated in an informal proficiency test regarding their work on bite marks. They were given seven sets of dental molds and asked to match them to four bite marks from real cases. They reached erroneous results 63 percent of the time. [60 Minutes] One bite mark study has shown that forensic dentists can't even determine if a bite mark is caused by human teeth. [Pema Levy / Mother Jones]
That didn't keep bite mark "expert" Michael West from testifying in trial after trial. In 1994, West testified that the bite mark pattern found on an 84-year-old victim's body matched Eddie Lee Howard's teeth. Based largely on West's testimony, the jury convicted Howard and sentenced him to death. Experts have since called bite mark testimony "scientifically unreliable." And sure enough, 14 years later, DNA testing on the knife believed to be the murder weapon excluded Howard as a contributor. Yet the state continues to argue that Howard's conviction should be upheld on the basis of West's testimony. [Radley Balko / Washington Post]
West, who in 1994 was suspended from the American Board of Forensic Odontology and basically forced to resign in 2006, is at least partially responsible for several other wrongful convictions as well. [Radley Balko / Washington Post]
West himself has even discredited his own testimony, now stating that he "no longer believe[s] in bite mark analysis. I don't think it should be used in court." [Innocence Project]
The FBI has found that fingerprint examiners could have an error rate, or false match call, as high as 1 in 306 cases, with another study indicating examiners get it wrong as often as 1 in every 18 cases. [Jordan Smith / The Intercept] A third study of 169 fingerprint examiners found a 7.5 percent false negative rate (where examiners erroneously found prints came from two different people), and a 0.1 percent false positive rate. [Kelly Servick / Science Mag]
In 2004, police accused American attorney Brandon Mayfield of the notorious Madrid train bombing after experts claimed his fingerprint matched one found on a bag of detonators. Eventually, four experts agreed with this finding. Police arrested him and detained him for two weeks until the police realized their mistake and were forced to release him. [Steve Pokin / Springfield News-Leader]
In Boston, Stephan Cowans was convicted, in part on fingerprint evidence, in the 1997 shooting of a police officer. But seven years later, DNA evidence exonerated him and an examiner stated that the match was faulty. [Innocence Project]
A 2012 review of the St. Paul, Minnesota, crime lab found that over 40 percent of fingerprint cases had "seriously deficient work." And "[d]ue to the complete lack of annotation of actions taken during the original examination process, it is difficult to determine the examination processes, including what work was attempted or accomplished." [Madeleine Baran / MPR News]
Firearm analysis
According to one study, firearm examiners may have a false positive rate as high as 2.2 percent, meaning analysts may erroneously declare a match as frequently as 1 in 46 times. This is a far cry from the "near perfect" accuracy that examiners often claim. [President's Council of Advisors on Science and Technology]
In 1993, a jury convicted Patrick Pursley of murder on the basis of firearms testimony. The experts declared that casings and bullets found on the scene matched a gun linked to Pursley "to the exclusion of all other firearms." Years later, an expert for the state agreed that the examiner should never have made such a definitive statement. Instead, he should have stated that Pursley's gun "couldn't be eliminated." In addition, the defense's experts found that Pursley's gun was not the source of the crime scene evidence. Digital imaging supported the defense. [Waiting for Justice / Northwestern Law Bluhm Legal Clinic] In 2017, a court granted Pursley a new trial. [Georgette Braun / Rockford Register Star]
Rethinking faulty forensics
Scientists from across the country are calling for the justice system to rethink its willingness to admit pattern-matching evidence.
In 2009, the National Research Council of the National Academy of Science released a groundbreaking report concluding that forensic science methods "typically lack mandatory and enforceable standards, founded on rigorous research and testing, certification requirements, and accreditation programs." [Peter Neufeld / New York Times]
In 2016, the President's Council of Advisors on Science and Technology (PCAST), a group of pre-eminent scientists, issued a scathing report on pattern-matching evidence. The report concluded that most of the field lacked "scientific validity" — i.e., research showing examiners could accurately and reliably do their jobs. [Jordan Smith / The Intercept] Until the field conducted better research proving its accuracy, the Council stated that forensic science had no place in the American courtroom. The study found that, regarding bite mark analysis, the error rate was so high that resources shouldn't be wasted to attempt to show it can be used accurately. [Radley Balko / Washington Post]
After the PCAST report came out, then-Attorney General Loretta Lynch, citing no studies, stated emphatically that "when used properly, forensic science evidence helps juries identify the guilty and clear the innocent." [Jordan Smith / The Intercept] "We appreciate [PCAST's] contribution to the field of scientific inquiry," Lynch said, "[but] the department will not be adopting the recommendations related to the admissibility of forensic science evidence." [Radley Balko / Washington Post]
The National District Attorneys Association (NDAA) called the PCAST report "scientifically irresponsible." [Jessica Pishko / The Nation] "Adopting any of their recommendations would have a devastating effect on the ability of law enforcement, prosecutors and the defense bar to fully investigate their cases, exclude innocent suspects, implicate the guilty, and achieve true justice at trial," the association noted. [Rebecca McCray / Take Part]
The NDAA also wrote that PCAST "clearly and obviously disregard[ed] large bodies of scientific evidence … and rel[ied], at times, on unreliable and discredited research." But when PCAST sent out a subsequent request for additional studies, neither the NDAA nor the Department of Justice identified any. [PCAST Addendum]
This problem is getting worse under the current administration. Attorney General Jeff Sessions has disbanded the National Commission on Forensic Science, formed to improve both the study and use of forensic science, and which had issued over 40 consensus recommendation documents to improve forensic science. [Suzanne Bell / Slate] He then developed a DOJ Task Force on Crime Reduction and Public Safety, tasked with "support[ing] law enforcement" and "restor[ing] public safety." [Pema Levy / Mother Jones]
But there are also new attempts to rein in the use of disproven forensic methods. In Texas, the Forensic Science Commission has called for a ban on bite marks. "I think pretty much everybody agrees that there is no scientific basis for a statistical probability associated with a bite mark," said Dr. Henry Kessler, chair of the subcommittee on bite mark analysis. [Meagan Flynn / Houston Press]
A bill before the Virginia General Assembly, now carried over until 2019, would provide individuals convicted on now-discredited forensic science a legal avenue to contest their convictions. The bill is modeled after similar legislation enacted in Texas and California. The Virginia Commonwealth's Attorneys Association opposes the legislation, arguing: "It allows all sorts of opportunities to 'game' the system." [Frank Green / Richmond Times-Dispatch]
Meanwhile, at least one judge has recognized the danger of forensic expert testimony. In a 2016 concurrence, Judge Catherine Easterly of the D.C. Court of Appeals lambasted expert testimony about toolmark matching: "As matters currently stand, a certainty statement regarding toolmark pattern matching has the same probative value as the vision of a psychic: it reflects nothing more than the individual's foundationless faith in what he believes to be true. This is not evidence on which we can in good conscience rely, particularly in criminal cases … [T]he District of Columbia courts must bar the admission of these certainty statements, whether or not the government has a policy that prohibits their elicitation. We cannot be complicit in their use." [Spencer S. Hsu / Washington Post]
Do you wonder how witchcraft and satanic children eating coven stories survive in this era of lies and misdemeanors and wrongful convictions? This article pushes back against what's coming out of the US WH and DOJ (and some DAs) spiel about forensic reliability. https://injusticetoday.com/faulty-forensics-explained-fe4d41157452
via #Forensics: The usual forensic failures described : DAs don't give much of a damn. — FORENSICS and LAW in FOCUS @ CSIDDS | News and Trends
adversarial criminal justice system Education ethics Forensic Protocols forensic science forensics justice system law Legal procedures protocols standardized UNIFORM LANGUAGE FOR TESTIMONY AND REPORTS (ULTRS)
Leave a comment Posted on November 3, 2017 November 3, 2017 Digital Forensics, Forensics
Focused Digital Forensic Methodology — Forensic Focus – Articles
Since the end of the 19th Century until the current time, law enforcement has been facing a rapid increase in computer-related crimes. In the present time, digital forensics has become an important aspect of not only law enforcement investigations, but also; counter-terrorism investigations, civil litigations, and investigating cyber-incidents. Due to rapid developing and evolving technology, these types of forensic investigations can become complex and intricate. However, creating a general framework for digital forensic professionals to follow during those investigations would lead to a successful retrieval of relevant digital evidence. The digital forensic framework or methodologies should be able to highlight all the proper phases that a digital forensic investigation would endure to ensure accurate and reliable results. One of the challenges that digital forensic professionals have been facing in the recent years is the volume of data submitted for analysis. Few digital forensic methodologies have been developed to provide a framework for the entire process and also offer techniques that would assist digital forensic professionals to reduce the amount of analyzed data. This paper proposes a methodology that focuses mostly on fulfilling the forensic aspect of digital forensic investigations, while also including techniques that can assist digital forensic practitioners in solving the data volume issue.
Focused Digital Forensic Methodology
Modern society has become very dependent on computers and technology to run all aspects of their lives. Technology has had a very positive impact on humanity, which can be easily proven with a short visit to any hospital and witnessing how computers and technology have become tools used to treat and save lives. However, computers have an indisputable disadvantage of being used as a tool to facilitate criminal activities. For instance, the sexual exploitation of children can be performed using the Internet, which would allow criminals to remain anonymous while preying on innocent children. The number of digital related crimes are increasing, which makes law enforcement agencies engaged in a constant battle against criminals who use this technology to commit crimes. As a result, digital forensics has become an important part of law enforcement investigations. Digital forensics is not only performed during law enforcement investigations but can also be conducted during the course of civil matters.
The fact that the information obtained from digital forensic investigations would and can be used as evidence during legal proceedings means that the entire process must be performed according to the legal standards. Perumal (2009) explained that the legal system requires digital forensic processes to be standardized and consistent. One of the issues that Perumal highlighted was the fact that digital evidence is very fragile and the use of improper methods could potentially alter or eliminate that evidence. There are a huge number of methodologies that have been developed all over the world, many of them were designed to target a specific type of technology (Selamat, Yusof, and Sahib, 2008). Also, many methodologies were developed to address requirements imposed by the legal system in certain jurisdictions. One of the methodologies that did not base their theory on technology or the law is the Integrated Digital Investigation Process (IDIP) Model. Carrier and Spafford (2003) explained that the IDIP Model is based on the Locard Exchange Principle, which is used to retrieve evidence from physical crime scenes. The IDIP Model uses the idea that when software programs were being executed in an electronic environment, electronic artifacts would most likely be created on the underlying device. Those artifacts can be retrieved and analyzed to obtain information about a certain incident or event.
This paper examines different literatures that present different types of digital forensic methodologies. Some of these methodologies have taken the focus away from the forensic aspect of digital forensic investigations. Instead, these methodologies have addressed crime scenes and other processes that are not related to the digital forensic field. Also, much research has been focused on creating solutions to the challenges that digital forensic practitioners are facing when conducting digital forensic investigations. One of the main challenges that multiple literatures have addressed is the constant increase in the volume of data that practitioners are acquiring and examining during investigations. This paper proposes a digital forensic methodology that would allow forensic practitioners to overcome the data volume issue and eliminate the lack of focus found in many methodologies.
As it was mentioned above, there are a large number of digital forensic methodologies that were developed all over the world. One of the first serious attempts to develop a standardized methodology that could be used during digital forensic investigations was in 1995. Pollitt (1995) utilized processes that were originally developed to handle physical evidence as a framework to create a methodology for digital forensic investigations. The author's approach to creating different phases being conducted during an investigation was inspired by many factors that the legal system considers when evaluating any type of evidence. The court would evaluate; whether the seizure was properly conducted, was there any alteration that occurred with the evidence, and what methods were used to examine the evidence. The proper performance of all these steps would allow any type of evidence to be admitted by the court. Pollitt (1995) developed a methodology that consisted of four phases; acquisition, identification, evaluation, and admission as evidence. This methodology focused mostly on the forensic aspect of the investigation and did not extend to other processes that other researchers have considered in their methodology; preparation, planning, and the search of physical crime scene.
Many digital forensic methodologies were developed after Pollitt's methodology. Some of those methodologies have used different terminology and sequencing of the phases that a forensic practitioner would have to perform throughout their investigations. Most of the methodologies have agreed on certain processes that are related to the forensic aspect of digital forensic investigations (Selamat et al., 2008). Selamat et al. studied 11 different digital forensic methodologies and concluded that all of them had common phases; preservation, collection, examination, analysis, and reporting. This means that all these researchers have agreed on these specific phases and any newly developed methodology would have to include similar phases.
According to Ruibin, Yun, and Gaertner (2005), the proper completion of any digital forensic investigation is directly related to conducting the processes that are similar to the ones highlighted by Selamat et al. (2008). Ruibin, Yun, and Gaertner also explained that in order to properly perform these phases, proper technique must be used. These techniques would ensure that the authenticity and reliability of the evidence is acceptable by the legal standards of the jurisdiction where the methodologies are being implemented. The use of the term legal is not foreign to digital forensic methodologies, as many researchers have addressed the importance of performing digital forensic investigations using the proper legal authorizations. For instance, the Integrated Digital Investigation Process (IDIP) Model has included obtaining legal authorization to perform a digital forensic investigation as one of the sub-phases of the Deployment Phase (Baryamureeba and Tushabe, 2004).
The IDIP Model was revised by Baryamureeba and Tushabe (2004) after noticing some practicality and clarity problems. Baryamureeba and Tushabe named the revised version as the Enhanced Integrated Digital Investigation Process (EIDIP) Model. In the EIDIP Model, the authors focused on two aspects, the sequence of the phases and clarity in regard to processing multiple crime scenes. The EIDIP proposed a modification to the deployment phase of the IDIP Model and included investigation of the physical and digital scenes as a way to arrive at the confirmation phase. Also, Baryamureeba and Tushabe added the Traceback phase, which aims at using information obtained from the victim's machine to trace back other machines used to initiate the incident.
Challenges Facing Current Methodologies
Technology has been developing on two aspects; hardware and software. For instance, a mobile device hardware has seen great advances that allows these devices to be able to perform complex operations efficiently. At the same time, the software operates on mobile devices has also undergone great advancements to be able to support the consumers' demand. However, these enormous changes in technology have affected the digital forensic methodologies, especially the ones that evolved around a certain set of technologies. Selamat et al. (2008) explained that there are many digital forensic methodologies that have been developed to target certain devices or a specific type of technology. The main problem with this type of methodology is the rapid changes of the underlying technology, which render these methodologies obsolete.
The legal system in different jurisdictions view digital forensics differently, which reflects on the methodologies used by forensic practitioners in those jurisdictions. According to Perumal (2009), "As computer forensic is a new regulation in Malaysia, there is a little consistency and standardization in the court and industry sector. As a result, it is not yet recognized as a formal 'Scientific' discipline in Malaysia" (p. 40). This means that the most affected jurisdictions are ones that have not developed a full understanding of computer forensics and the processes used to preserve and analyze electronic evidence. Also, the lack of understanding by the legal system would reduce the influence that the legal system has on shaping methodologies and making them acceptable by legal standards.
One of the other challenges related to digital forensic methodologies had been caused by the researchers who develop these methodologies. Some researchers have used titles and terminology in naming their methodologies that is not related to digital forensics. For instance, Baryamureeba and Tushabe (2004) named the fourth stage of the EIDIP Model as the Dynamite Phase, which includes Reconstruction and Communication as sub-phases. This lack of clarity in terminology would have a negative impact on any effort to help groups outside the digital forensic arena to have a better understanding of the processes used in the digital forensic field. As it was explained above, some jurisdictions across the globe are still unsure about digital forensics and the evidence obtained from a digital forensic investigation. This means that there would be advantages for researchers to utilize more modest and familiar terminology when addressing digital forensic methodologies. This simplicity in the terminology would assist the legal system in having a better understanding of the digital forensic processes.
The same challenges that the digital forensic field is currently facing can also be seen as challenges to digital forensic methodologies. Some of those challenges are; volume of data, encryption, anti-forensic techniques, and lack of standards. The reason these factors are perceived as challenging is because they have been slowing down the progression of digital forensic investigations. For instance, a fully encrypted computer system and an undisclosed encryption key would prevent practitioners from gaining access to the data, which ultimately imposes a challenge on the entire digital forensic process. One of the challenges that has been addressed by many researchers is the volume of data examined by forensic practitioners during digital forensic investigation. Examining a large amount of information during a digital forensic investigation would slow down the entire forensic process and affect the flow of operations for forensic laboratories.
Volume of Data
The increase in the volume of data was caused by the increasing sizes of electronic storage devices and at the same time the significant decrease in prices of those devices. According to Quick and Choo (2014), digital forensic practitioners have seen a significant increase in the amount of data that is being analyzed in every digital forensic examination. The authors explained that three factors have contributed to the volume of data that has become an issue for digital forensic practitioners; increase in the number of electronic devices for each investigation, the increase in the size of memory for those devices, and the number of investigations that require digital forensic examinations.
The significant increase in the volume of data has caused a great burden on forensic laboratories. Digital forensic practitioners are forced to spend longer times examining and analyzing larger data sets, which cause huge delays in completing digital forensic investigations. Quick and Choo (2014) explained that forensic laboratories have backlogs of work caused by the amount of time spend on each single examination. Some may argue that the increased amount of data can be an advantage as consumers are not forced to delete any data. However, Quick and Choo (2014) highlighted the seriousness of the data volume issue and stated, "Serious implications relating to increasing backlogs include; reduced sentences for convicted defendants due to the length of time waiting for results of digital forensic analysis, suspects committing suicide whilst waiting for analysis, and suspects denied access to family and children whilst waiting for analysis" (p. 274).
Current Solutions to the Data Volume Issue
Ruibin et al. (2005) offered a way to reduce the amount of data for each case by determining the relevant data based on the preliminary investigation. The relevant data for a certain case can be determined through two sources; case information and the person investigating the matter. Combining the information from both sources would assist in building a case profile, which can then be used to determine what type of information would be relevant for each forensic examination. The solution proposed by Ruibin et al. (2005) did not focus on using the technology to reduce the amount of data; however, there were other proposed solutions that suggested using technology to eliminate the data volume issue.
Neuner, Mulazzani, Schrittwieser, and Weippl (2015) proposed a technique that depends on technology to reduce the data volume. Their technique is based on the idea of file deduplication and file whitelisting. Deduplication and file whitelisting techniques would allow digital forensic practitioners to reduce the number of files that would have to be reviewed. Reducing the number of files would reduce the amount of time needed to complete the entire process. The authors defined the whitelisting technique as a way to compare a known list of hash values to the evidence and exclude any matches, as the contents of those files have already been determined. This list of hash values can either represent safe files or known contraband. The method offered by Neuner et al. (2015) is completely automated, and it would not require any human intervention, which means that no manpower is required to perform this task. Both solutions explained above are not controversial, as they utilize standard methods to locate the evidence. However, that is not the case with all solutions proposed to solve the data volume issue.
Quick and Choo (2014) explained that many researchers have addressed the issue of data volume through the use of the term sufficiency of examination. Those researchers did not focus on reducing the amount of data to be examined. Instead, they proposed limiting the search for electronic information only to the amount that would answer the main questions of the investigation. In other words, if a digital forensic practitioner examining a computer system for any evidence related to a child pornography investigation, the examination can be stopped once enough evidence was found to charge the suspect. This means that not all of the computer system would be examined and practitioners would be able to complete more examinations in a shorter period of time.
Some may argue that conducting a partial examination of the data could potentially lead to missing valuable digital evidence. For instance, in the example above concerning conducting a partial examination of child pornography evidence, conducting a full exam may lead to discovering pictures and videos of minors that are being sexually exploited. Those victims can potentially be identified and rescued. This means that conducting a partial examination of the evidence could possibly prevent those victims from being rescued. Still, assuming a full exam could lead to identifying other victims does not stand when confronted by the facts presented by Quick and Choo's (2014), which highlighted the fact that delaying the results of a forensic exam has grievous negative effects. These effects can be seen on suspects who are waiting a long time for forensic practitioners to conclude their exams. The same goes for the victims, as they are not able to get any closure during the investigation, as they all have to await the exam to be concluded.
The Proposed Methodology
Digital forensic practitioners continue to face a great deal of pressure from the challenges explained earlier. These challenges are placing obstacles in the way of examinations, in return causing practitioners to spend an extensive amount of time working on each investigation. However, it appears that researchers have not invested much effort into creating methodologies that would support practitioners to ease the pressure and eliminate the challenges. However, some may impose a compelling argument that not all challenges can be resolved in the context of the methodologies. For instance, data encryption is one of the issues that prevents practitioners from accessing the evidence and can be categorized as a technical challenge. This means that researchers would not be able to address this challenge in the context of a digital forensic methodology as methodologies are supposed to address higher level processes that occur during digital forensic investigations. Even though this argument seems compelling, practitioners can still create methodologies that are at least capable of reducing the workload pressure away from practitioners.
Selamat et al. (2008) described the Extended Model presented by Ciardhuain (2004) as a complete framework that provides clear stages for digital forensic investigations. Ciardhuain (2004) suggested that there are multiple steps that must be taken throughout digital forensic investigations; awareness, authorization, planning, notification, search and identification of evidence, collection, transport, storage, examination, hypotheses, presentation, proof/defense, and dissemination. Selamat et al. (2008) also explained that the Extended Model included all five phases that were agreed upon by many researchers. This means the remaining phases of the Extended Model are not related to digital forensics and removing them would not affect the authenticity or reliability of the electronic evidence. However, some may argue that the Extended Model was not intend to be conducted by only digital forensic practitioners, as many phases of the model can be performed by non-digital forensic practitioners. For instance, in a criminal investigation, completing the authorization phase can be performed by law enforcement personnel to grant forensic practitioners lawful access to the evidence. This means that the Extended Model, is a framework that is not only for practitioners, but is for all investigations that involve digital evidence.
This paper proposes a new methodology, Focused Digital Forensic Methodology (FDFM), that is capable of eliminating the data volume issue and the lack of focus with the current digital forensic methodologies. The FDFM is designed to be a reflection of the current workflow of law enforcement and civil investigations. The FDFM focuses on ensuring that digital forensic investigations are being conducted properly without overloading practitioners with unrelated activities. Further, the FDFM proposes techniques to reduce the volume of data to cut on time required to complete examinations of electronic evidence, especially on larger data sets. This paper proposes a new methodology, Focused Digital Forensic Methodology (FDFM), that is capable of eliminating the data volume issue and the lack of focus with the current digital forensic methodologies. The FDFM is designed to be a reflection of the current workflow of law enforcement and civil investigations. The FDFM focuses on ensuring that digital forensic investigations are being conducted properly without overloading practitioners with unrelated activities. Further, the FDFM proposes techniques to reduce the volume of data to cut on time required to complete examinations of electronic evidence, especially on larger data sets.
A quick review of the Extended Model would lead to a conclusion that it focuses on activities related to evidence that is considered common knowledge in the law enforcement field and digital forensic field. For instance, the transportation and storage activities of the EIDIP are two parts of evidence handling that is being trained to law enforcement personnel and digital forensic practitioners. So, it would not be of value to emphasiz the idea that digital forensic practitioners must transport and store the evidence after it was collected. For that reason, the FDFM has excluded aspects that can be considered common knowledge in the digital forensic field, which are related to the proper handling of evidence.
Phases of the FDFM
The FDFM is designed in a way similar to the IDIP and EIDIP, as it is broken down into multiple phases, which are further broken down into sub-phases. The FDFM is designed in a way similar to the IDIP and EIDIP, as it is broken down into multiple phases, which are further broken down into sub-phases.
Preparation Phases. The preparation phase can be applied in two situations; when creating a new digital forensic team and after completing a digital forensic investigation. This phase is mainly aimed at ensuring that digital forensic teams, no matter what their mission might be, are capable of initiating and completing an investigation properly and without any problems. Just as the case for the EIDIP, the focus in this phase is ensuring that the forensic team is trained and equipped for their assigned mission.
Training. To ensure the forensic team is executing a forensic methodology properly, they must have all the training that would equip all team members with the knowledge needed. This training does not only focus on how to collect or search evidence properly but also trains the members on how to use the tools needed during those processes. For instance, the team should have the knowledge needed regarding the value of preserving data. They should also be able to utilize any software or hardware tools that are capable of preserving and acquiring data from different platforms.
Equipment. There are many tools that digital forensic professionals utilize during investigations that are capable of serving different purposes. One of the functions that those tools are able to accomplish is automating different processes during the investigation, and completing those jobs in a timely manner. Depending on the main mission of the forensic team, tools and equipment must be available to ensure a proper and fast completion of any digital investigation.
On-Scene Phases. This phase focuses on processes that would be accomplished in the event that a digital forensic team was called in to assist with executing search warrants or even preserving data for a civil litigation.
Physical Preservation. During this phase, digital forensic practitioners ensure that any item that may contain electronic information of value is protected. This protection would ensure that no damage would be inflected on any electronic device that can cause the loss of the information within. For instance, if a digital forensic practitioner found one of the items sought during the search of a residence, this item must be kept in a location under the control of the searching team. This means that any occupant in the residence would not be able to cause any damage to the device, which they would possibly attempt if they believed that it contained incriminating evidence.
Electronic Isolation. The other part of the preservation is ensuring that the information within the collected device is preserved by eliminating any electronic interference. An item like a mobile device would have to be isolated from the cellular network to ensure that no one is capable of damaging or changing the data remotely. The same case applies to computers or other items with network connectivity, as suspects could connect remotely to those devices and attempt to eliminate any information that is potentially damaging to their case. Electronic Isolation. The other part of the preservation is ensuring that the information within the collected device is preserved by eliminating any electronic interference. An item like a mobile device would have to be isolated from the cellular network to ensure that no one is capable of damaging or changing the data remotely. The same case applies to computers or other items with network connectivity, as suspects could connect remotely to those devices and attempt to eliminate any information that is potentially damaging to their case.
Electronic Preservation. The last part of preservation is creating a complete or partial duplicate of the targeted electronic information. The created copy would ensure that the electronic evidence is preserved in a forensic image. In the event that the devices were not supposed to be removed from the scene, forensic images would have to be created on scene, which can then be taken back to the laboratory for examination. A partial collection can also be conducted during this phase, which would be especially advantageous for civil litigation purposes. In those cases, the collection of an entire computer system is not recommended, and practitioners would have to search for and collect only the relevant data.
Laboratory Phases. These phases are conducted when the team is at the laboratory and have all the evidence or forensic images collected from the scene. Prior to interacting with the evidence, an attempt would be made to reduce the volume of data that an examiner would have to process and analyze. The reduction of data volume is crucial for cases that have a huge number of electronic devices and a large volume of storage for electronic information. As it was explained earlier, reducing the volume of data would expedite the examination of the evidence and allow for a better workflow. Once the reduction of data has been completed, examiners can begin processing and analyzing data.
Building Case Profile. This phase is somewhat similar to the creation of a case profile presented by Ruibin et al. (2005). These authors suggested using input from the investigation to identify the type of information that a digital forensic practitioner would need to focus on finding during the examination. For instance, if the case is related to pictures of evidentiary value, then a practitioner would need to be focused on reviewing all the pictures found on a device, without the need to focus on any other type of electronic information. For the FDFM, building a case profile would begin, just as the case for Ruibin et al. (2005), with obtaining information from the investigating agency regarding their investigation. The obtained information must focus specifically on the relationship between the electronic evidence and the incident under investigation. In other words, the investigating agency would have to provide information about what role the devices played in the incident. For instance, a mobile device would be submitted to the digital forensic team as part of a rape investigation. The investigating agency would have to prove how the mobile device was related to the rape incident. In these situations, the phone could have been used by the suspect to communicate with or lure the victim into a certain location. Building Case Profile. This phase is somewhat similar to the creation of a case profile presented by Ruibin et al. (2005). These authors suggested using input from the investigation to identify the type of information that a digital forensic practitioner would need to focus on finding during the examination. For instance, if the case is related to pictures of evidentiary value, then a practitioner would need to be focused on reviewing all the pictures found on a device, without the need to focus on any other type of electronic information. For the FDFM, building a case profile would begin, just as the case for Ruibin et al. (2005), with obtaining information from the investigating agency regarding their investigation. The obtained information must focus specifically on the relationship between the electronic evidence and the incident under investigation. In other words, the investigating agency would have to provide information about what role the devices played in the incident. For instance, a mobile device would be submitted to the digital forensic team as part of a rape investigation. The investigating agency would have to prove how the mobile device was related to the rape incident. In these situations, the phone could have been used by the suspect to communicate with or lure the victim into a certain location.
Once all the information was obtained regarding the investigation and the evidence, the type of data relevant to the investigation can be determined. In the example above regarding the rape case, the suspect may have used text messages to communicate with the suspect, which makes any text base communication between both parties relevant and must be reviewed and analyzed. In some cases, determining the approximate size of information sought can also be relevant and would allow for the examination to be even more focused. For instance, an investigating agency submitted one 500 gigabyte external drive and one 8 gigabyte thumb drive to the digital forensic team for examination. The investigation was seeking documents approximately 30 gigabytes in size relevant to a fraud case. In this situation, a forensic practitioner would focus on the external drive as it most likely contains the documents because it is more than 20 gigabytes in size. In the same sense, the 8-gigabyte thumb drive most likely does not have the documents because of its small size.
The next step of the case profile is determining the most relevant type of devices based on the information obtained thus far about the investigation. If the examination is seeking text-based messages sent to the victim, then it likely means that a mobile device was used to send those messages. However, this does not mean that a computer cannot be used to send such messages, but a mobile device is the most likely suspect in this situation. Then, the profile can provide further emphasis on the possibility of a mobile device being the source of the relevant messages. It is apparent from the above that building a case profile would require an experienced digital forensic practitioner, using prior experience and knowledge while building the case profile would result in a more accurate and realistic conclusion. The next step of the case profile is determining the most relevant type of devices based on the information obtained thus far about the investigation. If the examination is seeking text-based messages sent to the victim, then it likely means that a mobile device was used to send those messages. However, this does not mean that a computer cannot be used to send such messages, but a mobile device is the most likely suspect in this situation. Then, the profile can provide further emphasis on the possibility of a mobile device being the source of the relevant messages. It is apparent from the above that building a case profile would require an experienced digital forensic practitioner, using prior experience and knowledge while building the case profile would result in a more accurate and realistic conclusion.
The final step of the case profile is setting goals that the investigation is hoping to accomplish at the end of the examination. These goals are based on all the information gathered thus far and how the evidence was going to prove or disprove an incident or event. For instance, in the example of the rape investigation mentioned above, retrieving the text messages from the mobile device is the first goal to show that the suspect had lured the victim to the crime scene. The timeline of those messages is another piece of information that would corroborate the victim's statement regarding different events prior to the incident. While examining the mobile device, these goals would make it clear to the digital forensic practitioner what the expected results following the examination of the device. The final step of the case profile is setting goals that the investigation is hoping to accomplish at the end of the examination. These goals are based on all the information gathered thus far and how the evidence was going to prove or disprove an incident or event. For instance, in the example of the rape investigation mentioned above, retrieving the text messages from the mobile device is the first goal to show that the suspect had lured the victim to the crime scene. The timeline of those messages is another piece of information that would corroborate the victim's statement regarding different events prior to the incident. While examining the mobile device, these goals would make it clear to the digital forensic practitioner what the expected results following the examination of the device.
In civil litigation cases and even criminal cases, it would be beneficial during this phase to generate a list of keyword searches that could be used during the examination process. Those keywords must be related directly to the evidence and based on the information obtained about the evidence. When dealing with civil litigation cases, the keyword list would become the main method used to locate any responsive and relevant electronic information. The words added to the list must also be related to the goals setup to be accomplished at the end of the investigation. For instance, if the civil case is related to patent infringement, then the keywords would reveal documents or data that could prove or disprove the allegations submitted by one party against the other.
Evaluation of the Evidence. This evaluation of the evidence would have to occur based on the case profile that was created during the previous phase. The main goal of this phase is to exclude any device that does not match the case profile and most likely would not hold any information sought during the examination of the evidence. Excluding items that do not have relevant information from being examined would reduce the amount of information that a digital forensic practitioner examines in each case. This would ultimately cut on the amount of time needed to complete the examinations and give the investigators faster results. As it was explained above, the case profile would determine the type of electronic information, the timeline related to the information, the size of the electronic information, and other aspects of the evidence. Using the generated profile, the items of evidence can be listed in a way that the device most likely containing the information would be placed on the top of the list. The rest of the devices would be placed in the same way, which is based on the likelihood that they would contain the targeted data. Based on this list, the last item of the list would be least likely to contain information relevant to the investigation.
Forensic Acquisition. During this phase, any data that was not acquired or preserved on scene would be imaged. The imaging process would focus on the items that are on the top of the list that was generated during the Evaluation of the Evidence phase. This means that only items that are believed to hold the relevant data would be acquired and not the entire list of items. This would save on the storage space required to save all the forensic images to and also reduce the time required for imaging.
Partial Examination/Analysis. Many digital forensic models separate the examination phase from the analysis phase, just as the case for the Abstract Digital Forensic Model (Reith, Carr, and Gunsch, 2002). Those models assume that a digital forensic practitioner would search the evidence for any relevant data during the examination phase. Then, an analysis would be conducted during the analysis phase to determine the significance of the information found during the examination phase. In the FDFM, those two phases are combined in one phase as they cannot be separated since they occur at the exact same moment during the search for the evidence. The FDFM proposes creating a case profile prior to examining the evidence, which means that a digital forensic practitioner would know what to search for and the significance of the information beforehand. So, while searching for the evidence, examiners would be able to determine the significance of the information as it is being located.
An example of the situation explained above is the rape incident that was mentioned earlier and the mobile device that holds the information related to the incident. At the time when the practitioner they had prior knowledge that the targeted information related to luring the victim to the incident location was in the text messages. While reviewing the text messages, the digital forensic practitioner found a message that showed how the suspect and victim had met. Then, on the day of the incident, other messages were found showing how the victim was lured to the location of the incident. As the forensic practitioner is reviewing the messages, they are evaluating the information simultaneously and weighing the significance of the pieces of information as it is being found. As each text message is going to add another piece of information related to the incident. At the end of this phase, the forensic practitioner will have a full picture of what happened on that day and any other information related to the incident. It would not be practical for the forensic practitioner to go back and reanalyze information that was previously analyzed as the information was being found. It is also worth mentioning that digital forensic practitioners usually mark the relevant data as it is being found to ensure that it is being included in the final report generated by the tool used to review the evidence. An example of the situation explained above is the rape incident that was mentioned earlier and the mobile device that holds the information related to the incident. At the time when the practitioner they had prior knowledge that the targeted information related to luring the victim to the incident location was in the text messages. While reviewing the text messages, the digital forensic practitioner found a message that showed how the suspect and victim had met. Then, on the day of the incident, other messages were found showing how the victim was lured to the location of the incident. As the forensic practitioner is reviewing the messages, they are evaluating the information simultaneously and weighing the significance of the pieces of information as it is being found. As each text message is going to add another piece of information related to the incident. At the end of this phase, the forensic practitioner will have a full picture of what happened on that day and any other information related to the incident. It would not be practical for the forensic practitioner to go back and reanalyze information that was previously analyzed as the information was being found. It is also worth mentioning that digital forensic practitioners usually mark the relevant data as it is being found to ensure that it is being included in the final report generated by the tool used to review the evidence.
The FDFM suggests the use of a method that was referenced by Quick et al. (2014), which aims at conducting a partial examination and analysis of the evidence as a solution for the data volume issue. According to Quick et al. (2014), the digital forensic practitioner would be, "doing enough examination to answer the required questions, and no more" (p. 282). The same concept can be applied using the FDFM, as digital forensic practitioners conduct examinations only to accomplish the goals setup during the Building Case Profile phase. The examination would be performed in the same sequence of relevance as determined during the Evaluation of the Evidence phase. This means that the examination would begin with the more relevant items and continue down the list until all the goals are accomplished. One of the greatest benefits of conducting partial examinations of the evidence is maintaining the privacy of the owners. For instance, mobile devices contain a vast amount of private information about the owners. This means that the more information to be reviewed, the more loss of privacy that would occur. Limiting the examination to the need of the investigation would assist in maintaining a certain limit of privacy for the owner of the data.
Reporting. During this phase, all the information found during the examination would be placed in a report to inform the investigating agency of the findings. There are many report formats used by different agencies. However, all formats have one thing in common, which is that they are all driven by the findings of the examination and not opinions. Reports that are supported by solid evidence are hard to dispute, as the evidence behind the information in those reports would suppress any arguments.
There are many literatures that propose different types of methodologies that have different focuses. However, many of those methodologies have included phases that are not related to the forensic aspect of those methodologies. Many researchers also addressed the issue of the volume of data that is causing huge delays with digital forensic exams. The proposed methodology, FDFM, allows digital forensic professionals to be focused more on forensics during any digital forensic investigation. This methodology has excluded any phases that were included in other methodologies and are considered common knowledge within the digital forensic field. The proposed methodology also addressed one of the biggest challenges for digital forensic investigations, which is the volume of data. The FDFM proposed two methods that would allow for reduction in the volume of data, excluding devices that do not contain relevant information and conducting partial examinations. Both techniques can be applied only after a case profile has been generated based on the information obtained by the investigating agency. Future research can be conducted by focusing on integrating other techniques to the FDFM that would eliminate other challenges of digital forensic investigations.
Agarwal, A., Gupta, M., & Gupta, S. (2011). Systematic digital forensic investigation model. International Journal of Computer Science and Security (IJCSS), 5(1), 118-131.
Baryamureeba, V., & Tushabe, F. (2004). The Enhanced Digital Investigation Process Model. Proceedings of the Digital Forensic Research Conference. Baltimore, MD.
Carrier, B., & Spafford, E. H. (2003). Getting physical with the Digital Investigation Process. International Journal of Digital Evidence, 2(2), 1-20.Carrier, B., & Spafford, E. H. (2003). Getting physical with the Digital Investigation Process. International Journal of Digital Evidence, 2(2), 1-20.
Ciardhuain, S. O. (2004). An extended model of cybercrime investigations. International Journal of Digital Evidence, 3(1), 1-22.
Neuner, S., Mulazzani, M., Schrittwieser, S., & Weippl, E. (2015). Gradually improving the forensic process. In the 10th International Conference on Availability, Reliability and Security, 404-410. IEEE.
Perumal, S. (2009). Digital forensic model based on Malaysian investigation process. International Journal of Computer Science and Security (IJCSS), 9(8), 38-44.
Pollitt, M. M. (1995). Computer forensics: An approach to evidence in cyberspace. In the 18th National Information Systems Security Conference, 487-491. Baltimore, MD.
Quick, D., & Choo, K. R. (2014). Impact of increasing volume of digital forensic data: A survey and future research challenges. Digital Investigation, 11(4), 273-294.
Reith, M., Carr, C., & Gunsch, G. (2002). An examination of the digital forensic models. International Journal of Digital Evidence, 1(3), 1-12.
Ruibin, G., Yun, T., & Gaertner, M. (2005). Case-relevance information investigation: binding computer intelligence to the current computer forensic framework. International Journal of Digital Evidence, 4(1), 147-67.
Selamat, S. R., Yusof, R., & Sahib, S. (2008). Mapping process of digital forensic investigation framework. International Journal of Computer Science and Network Security, 8(10), 163-169.
Haider Khaleel is a Digital Forensics Examiner with the US Army, previously a field agent with Army CID. Haider received a Master's Degree in Digital Forensics Science from Champlain College. The ideas presented in this article do not reflect the polices, procedure, and regulations of the author's agency.
Correspondence concerning this article should be addressed to Haider H. Khaleel, Champlain College, Burlington, VT 05402. haider.khaleel@mymail.champlain.edu
by Haider H. Khaleel Abstract Since the end of the 19th Century until the current time, law enforcement has been facing a rapid increase in computer-related crimes. In the present time, digital forensics has become an important aspect of not only law enforcement investigations, but also; counter-terrorism investigations, civil litigations, and investigating cyber-incidents. Due to […]
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Leave a comment Posted on August 26, 2017 Forensics
The Top Five Computer Forensic Tools — Cyber Incision
Forensic tools are something that are required to be updated on a regular basis. Whether because of patches, new hardware, or just a changing technological landscape, tools must be maintained in order to remain relevant. The ongoing support is just one of the reasons that the tools discussed in this article are the most used […]
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Leave a comment Posted on June 29, 2017 Forensics
6 Forensic Advancements via Sue Colleta
The forensic community works tirelessly to improve techniques to aid law enforcement, and much of this work is done at body farms across the country. The Texas body farm has conducted some amazing work as of late. I've complied my top six forensic advancements, which I think you'll find fascinating. 6 Mind-Blowing Forensic Advancements
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Leave a comment Posted on December 2, 2016 December 2, 2016 Forensics, Uncategorized
Forensic Linguistics: 101 — April Rink
If you have ever heard a song for the first time and recognized the artist because of his/her voice, then you have employed the techniques of linguistics. Or maybe you've left a note for your mother on the kitchen counter asking her to buy Doritos and though you didn't sign it, she knew your handwriting. In a […]
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Leave a comment Posted on November 2, 2016 November 2, 2016 Forensics, Uncategorized
Conservation Connection – Understanding decomposer lifeforms
ST. LOUIS (KPLR) – Naturalist Curtis Parsons visits KPLR 11 News at Noon to show us the mysterious world of decomposers. Q. What are decomposers? • Decomposers are organisms that help break down dead and decaying matter • Some decomposers specialize on breaking down plants or animals • Today we'll focus on animal decomposers, especially insects…
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Leave a comment Posted on October 10, 2016 October 10, 2016 Forensics, Uncategorized
Spent nuclear fuel canisters vulnerable to failure as they age — nuclear-news
Premature failure of U.S. spent nuclear fuel storage canisters, San Onofre Safety.org, by Donna Gilmore "……Stainless Steel Dry Canister Problems Darrell Dunn, an NRC materials engineer, stated stainless steel dry storage canisters are vulnerable to failure within about 25 – 42 years. If any of the fuel cladding in the canister fails, there is no protective barrier and […]
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Since 2001, the Martha Jefferson Hospital Foundation has held a special covenant with community donors to assure that gifted funds are accurately documented, acknowledged, recognized and tracked per their restricted use for the benefit of patients, staff and the community served by Sentara Martha Jefferson Hospital. The Foundation's Board helps to create a culture of philanthropy, engagement and support for the Hospital with the ultimate goal identified in the Foundation's mission to secure and steward philanthropic resources to meet priority needs and initiatives of Sentara Martha Jefferson Hospital.
Each year through the Foundation, thousands of you make directed donations to support emerging or established priorities, show gratitude for care received or support the Hospital through one of our great events. Large or modest, each donor and their gift is honored with that special commitment from the Foundation Board and Staff. While we can never say thank you enough, nor overly emphasize philanthropy's impact, know that the Foundation takes this role and responsibility to heart in pursuing its donor-directed mission.
High-Risk Breast Program: to identify, guide and support women at higher risk of developing breast cancer.
Cancer Survivorship Program: to embrace the growing number of patients living as cancer survivors and to help ensure a supported transition from their intense treatment phase.
Family Caregiver Support Program: to offer nonjudgemental emotional support to family caregivers, assist them with the skills they need to care for loved ones and provide a trusted referral, as appropriate.
Center for Clinical Education: to support our incumbent non-nursing professional staff and their specialty education needs, and to work with our community to develop career pathways in support of workforce development in needed healthcare roles.


Healthy Eating Pyramid is the foundation of your daily exercise and weight control. It has a strong influence in staying healthy.
The logic is simple because exercise and weight control is linked to each other with an uncomplicated rule of balancing energy.
When you burn as many calories each day as you take it, there is nothing would be left storing in your fat cells, and your weight remains the same. However, if you eat more than you burn, then you will end up adding more fats and pounds in your body.
Whole Grains will give us carbohydrates such as oatmeal, whole-wheat bread, and brown rice. Our body needs carbohydrates that give us energy.
Healthy Fats and Oils is surprisingly at the near base, indicating that it's okay to have it although not all types of fats are allowed but the healthy fats like olive, canola, soy, corn, sunflower, peanut and other vegetable oils only.
Vegetables and Fruits has an ample advantage. It will help you to decrease the chances of heart attack or stroke, protecting you to some types of cancer, lowering your blood pressure and helping you to avoid some intestinal ailment and can guard you against muscular degeneration. Potatoes are not counted as the vegetable because it has the same effect on blood sugar like refined grains and sweets, and uses sparingly in the Healthy Eating Pyramid.
Nuts, Seeds, Beans, and Tofu are plant foods that is excellent source of fiber, protein, vitamins and minerals like black beans, garbanzos, lentils, etc. and some other nuts that contains healthy fats like almonds, walnuts, peanuts, etc. are good for your heart. Eating this kind of beans and nuts instead of red meat or process meat can help you lowering the risk of having heart disease and diabetes.
Fish, Poultry, and Eggs are also important for it can as well be the source of protein. Eating fish can reduce heart disease while chicken are can be low saturated fat. An egg a day is fine but for people with diabetes or heart disease should only have it for three times a week.
Dairy or Vitamin D and Calcium will help us to have strong bones. However, we should limit it in 1 to 2 servings per day only. High dairy intakes can be associated will increase the risk of ovarian cancers or fatal prostate.
Nevertheless, you can get calcium by taking calcium supplements and vitamin D to meet your daily needs.
Red Meat, Processed Meat, Butter, Refined Grains, Potatoes, Sugary Drinks and Sweets, and Salts are all staples at the top because it can cause increases in blood sugar which can be lead to weight gain, diabetes, hear disease and other chronic diseases.
Just remember the basic guidelines in Healthy Eating Pyramid that healthy diet is having more foods from the base of the pyramid than from the higher levels of the pyramid. Choosing a variety of fresh, whole foods from the groups will ensure you are getting the right nutrients that you need and the only foods that are off-limits are those who are on top of the pyramids.
Following this will help you decide which one to place in your Healthy Eating Plate for more effective and healthy you!


text:
How do protective coatings affect the lifetime of bridges?
I'm trying to understand the importance of protective coatings on steel structures like the Golden Gate Bridge. For example, if we stopped maintenance on the Golden Gate Bridge today and left it packed with empty cars, what would be its expected lifetime (until a car falls into the water) and the variance of that lifetime? If we additionally removed all of the paint/coatings on any steel parts, what would be the expected lifetime and variance? I'm hoping for a rough answer from an expert in the field.
civil-engineering bridges corrosion
bobuhito
bobuhitobobuhito
$\begingroup$ Wow. That edited question is significantly different. And (in my opinion) almost completely unanswerable. Unless someone on here happens to have carried out a numerical assessment of the Golden Gate Bridge recently, in order to know its reserve capacity, and also feels like doing calculations on corrosion. You ask for variance, requiring some sort of statistical analysis too. Oh, and I should point out that it being full of empty cars is nowhere near its design loading, meaning that's a whole new calculation compared to any assessment of the structure. $\endgroup$
– AndyT
$\begingroup$ So - the original question was too broad. I'd say the edited question is far too specific. If you want to know about coatings, maybe ask a question about coatings? How about "What coatings are used on steel structures to prevent corrosion?" $\endgroup$
$\begingroup$ I cleaned up comments, since the question was rewritten. $\endgroup$
– Air
$\begingroup$ The answer is 42.315 years. If you don't believe me, you'll just have to run the experiment. $\endgroup$
$\begingroup$ "I know it's still a tough question, but that's what the best engineers get paid highly to answer." So you are looking for a million dollar answer given freely and in the limited space here? That might be expecting too much. $\endgroup$
– hazzey ♦
If you are really considering catastrophic failure, what you are asking actually has several parts. The first is the coatings aspect, the second is the metal structure, the third is the connections, the fourth is the cables, the fifth would be the substructure and the sixth is the foundation. A failure of any one of these systems (with the exception of coatings) could lead to the type of catastrophic failure you are considering.
The Golden Gate Bridge was constructed in the mid to late 1930s (around 1933 to 1938 I believe, see timeline) and I will come back to this in later paragraphs.
It is important to note that the loading conditions currently on the bridge in terms of axle loads and traffic volumes are perhaps magnitudes higher than the original designer could have envisaged. These loads will have a significant impact upon the risk of catastrophic failure, and for this reason there has likely been significant structural strengthening carried out in the Golden Gate Bridge over the years.
One thing that I noted on the timeline was that there already has been a catastrophic failure of the upper and lower decks due to a 7.1 earthquake on October 17, 1989.
Generally speaking coatings are designed for a given service life. Provided that they are applied with adequate workmanship and quality, for a given material in a given environment the performance is fairly predictable; ie they will lose their protective capability over time due to oxidation, temperature, solar radiation and abrasion effects. Many designs are geared towards a certain loss in terms of mils/yr, so that for a 10 year service interval there will be a certain dry film thickness of coating specified. NASA Kennedy Space Center has detailed documentation on these issues. Once this protective measure is breached then corrosion of the underlying steel may take place. So it is important that coatings are renewed at regular intervals.
Structural steel generally has a well defined atmospheric corrosion rate for a given environment and this is based upon it's proximity to the sea. Studies done by NASA in Florida on metal coupons from seafront to a distance inland about 30 km indicate that the danger zone is within roughly 1000 m of the sea. After that the atmospheric corrosion rates dropped off significantly. But the Golden Gate Bridge is clearly within a danger zone. From NASA data, Pont Reyes, California would have an expected atmospheric corrosion rate of about 20 mils/yr. Certainly Caltrans will have similar research data. If left unprotected by coatings, and if this number were valid for your immediate environment, then you could take the thickness of the structural section and reduce exposed surfaces by 20 mils/yr to roughly estimate what would happen to an unprotected structure with time. Of course the NASA studies are using modern grades of steel, the Golden Gate steel was produced in the 1930s, so there could be a greater annual loss. This is atmospheric corrosion; the structural steel that is within range of the seawater spray and splash zone will actually experience a more severe corrosion condition, and protective measures there will likely include sacrificial anode systems in addition to coatings. That is, an anode material such as zinc is electrically connected to the structural steel in seawater spray exposure zones because it is more susceptible to corrosion. It is sacrificed in order to direct corrosion activity away from the structural steel. These also must be replaced at intervals. There are also impressed current systems too, these are called cathodic protection and they work in a similar fashion.
Now what does this mean for the structure? A structural analysis would be required to determine where the critical loading point occurs; ie where the force of a fully loaded bridge would exceed the ultimate loading capacity of the corroded, diminished sections. When structural elements oxidize, the oxidized portion of the section can no longer support load, and the remaining sound steel under the corrosion product is the issue of importance. But you can see that if coatings/protective measures are not reapplied when required then the corrosion rate of structural steel could endanger the structural capacity of the bridge very quickly, perhaps within a few years.
Structural connections are very sensitive to fatigue and this also exacerbates their sensitivity to corrosion. In other words elements of higher stress cycling are also more susceptible to corrosion. The two factors are quite significant in determining lifespan. For this reason, and I do not have any specific knowledge of this matter for the Golden Gate Bridge, I suspect that the connections in the bridge today have been essentially entirely replaced, perhaps several times at high stress locations, since initial construction. These are the most critical part of the structural steel framework for the bridge, from a load and lifespan perspective. If they fail, then catastrophic failure follows. It is also possible that additional protective measures are taken for the connections in terms of additional coating thickness or specialized treatments.
The Golden Gate Bridge is a suspension bridge so the cables are an integral part of the load capacity of the structure. These cables normally would have a protective sleeve around them to ensure that they are isolated from the environment, and cable sleeves today are typically filled with protective lubricants. I do not have any knowledge specific to the Golden Gate Bridge but I would expect that the design does include protective sleeves, at least for the main cables. Corrosion of cables can very quickly lead to very serious structural problems and for that reason they are inspected frequently. One of the problems with sleeved cables is that the cable itself is hidden from view, unlike other elements of the bridge, so the inspection would require non-destructive techniques that may include ultrasonic and radiographic testing. I am not aware of any loss per year allowances for cables, if they show any signs of corrosion then I would expect they will be scheduled for replacement or repair.
The concrete substructure (foundation piers) elements would take the brunt of the most severe exposure condition, that is sea spray and splash zone. Wetting and drying conditions in the sea environment are the most corrosive. Here any exposed concrete may degrade at the surface due to salt scaling effects and this, along with carbonation (ie conversion of calcium hydroxide to calcium carbonate in the concrete) can reduce the effective protection of reinforcing steel in the concrete by reducing the thickness of the protective concrete cover.
There are generally well known formulas for concrete in sea splash and spray zones for time to corrosion of reinforcing steel. Pioneers in this field (among many others since) were Beaton and Stratfull (1962) and Stratfull (1964 and 1967) of Caltrans. More recently Collepardi and Clear have introduced improvements (Collepardi introduced diffusion theory in the early 1970s and Clear's work in the mid 1970s was a refinement of the Beaton and Stratfull analysis). These formulas are used at the time of design and can be used throughout the life of the structure for estimating remaining life. This has to do with the concentration of chlorides with depth in the concrete, that are carried into the concrete by seawater and increase in concentration with time.
For this reason protective coatings and other systems such as cathodic protection are used to prevent reinforcing steel corrosion. I would suspect that one or more of these treatments are in place at the Golden Gate Bridge, and I would also expect that portions of the concrete and reinforcement have been replaced in the past.
Nonetheless, if the corrosion were to be left untreated in the substructure then there could be a very serious catastrophic failure. If left completely untreated, the concrete of the type used on the Golden Gate Bridge in the 1930's would probably reach a critical stage within 25 to 30 years. The age of the bridge, being some 75 to 80 years of age means that this substructure concrete has likely had substantial repair, replacement and protective treatment by now.
Concrete foundations, if permanently below the low tide line, generally are not at high risk, but can present problems. It is not commonly known, but the concrete of foundations of the Golden Gate Bridge contain Pozzolans, which was an advanced technique for its time. Pozzolans are usually added for improved durability, but they can play a major role in reducing temperature related distortions that can lead to cracking.
In fact one of the more tragic bridge collapses in history occurred for this very reason during May 1980. The Sunshine Skyway Bridge in Tampa collapsed killing 35 persons. The engineer's investigation concluded that the cause of the collapse was directly attributable to cracks in the below water pier foundations due to the high temperature of the concrete at the time of construction.
AsymLabsAsymLabs
$\begingroup$ Wow, this is great and therefore will take me a few days to digest... I hadn't even been thinking about the earthquake risk, which as you pointed out, is determining the lifetime! So, please let me also assume that there are no earthquakes (or nuclear blasts or whatever), so that my underlying reliability lifetime concern stays. $\endgroup$
– bobuhito
$\begingroup$ @bobuhito Today when a bridge of this nature is conceived, there will be a design basis that includes stated lifetime goals. For example the designed service life may be specified as 150 years, coatings may be specified as 10 or 20 years, and other aspects, such as mechanical elements, expansion joints, etc, may be specified as something else. There may also be maintenance intervals, say not less than 50 years. So for a given structural purpose or function, the design will be implemented according to life requirements, and this will also largely govern the cost of construction. $\endgroup$
– AsymLabs
The goal of using protective coating/paint is to reduce corrosion of the metal framework. The degree of corrosion varies from the top to sea level and depends on several parameters such as salinity of rain/ocean, humidity, avg. temperature, the acidity of rain, so on so forth.
The principle behind protective coatings may differ in terms of layers, but often, a primer containing a less noble metal is applied directly onto the metal whereto a top and even a middle layer is added, which contributes with resistance to UV light, moisture, etc.
Edit 1 - additional info
If this was insufficient, here is a detailed explanation of the principles of coatings. Here is what I known from courses and through my work at Hempel.
The composition of paint is build from four components: 1. a binder, 2. a solvent, 3. pigments and 4. additives.
The binder
The binder functions as an adhesive and is non-volatile. The transition (of the paint) from liquid to a solid is determined by the binder as well as other parameters such as chemical, weather and corrosive resistivity.
The solvent
The solvent contributes with low visocity so that the coating me be applied more easily. Solvents are volatile compounds, that during the curing, evaporates leaving the 'film' behind. The film consist of intertwined molecules forming a polymer. While common, solvents are not a necessity, as the binder may contribute with a proper viscosity. Notice that water can be used as a solvent (waterborne paints), however a compound must be present in order to mingle the dispersed particles.
Pigments are added to achieve a desired color. An other function of filler material is to reduce production cost.
Additives contributes with product-enhancing attributes such as extending shelf life, reduce curing time, improve moisturization of pigments, etc.
Coatings are classified into two groups on basis of curing: physical drying or chemical curing. In brief, paints containing evaporating solvents are classified as physical drying, in contrary to paints that requires oxidative processes, as these are classified as chemically curing. This happens as gas species such as $\text{O}_2$, $\text{H}_2\text{O}$ and $\text{CO}_2$ causes oxidation which starts the polymerization process.
Corrosive protecting coatings
To briefly describe why corrosion happens, one must look at the chemistry of oxidation. It is energetically more favorable for a metal to be oxidized. I. e. in the presence of water or air, the following reaction will eventually occur. \begin{equation} \text{Fe} + \left[\text{O}\right] \rightarrow \text{Fe}^{++}+2\text{e}^- \end{equation}
There are generally 3 ways used to prevent the above reaction.
Formation of physical barriers that retards the diffusion of water and $\text{O}_2$. Barrier effect. Different compounds are used to achieve this effect: epoxy/bitumen/tar produces a barrier with low permeability for the water. Large pigments can produce an effect similar to, where the pigments are aligned parallel to the surface, resulting in a longer path the water must travel before reaching the metal surface.
Ensure contact between a less noble metal and the metal-surface thus achieving a galvanic effect. Galvanic effect. To protect iron, metallic zinc is often used in abundance. This however requires the zinc throughout is in contact with it self and the surface. Zincprimers are not used in submerged surfaces, as the zinc salts are easily soluble.
or ensure the water reacts with compounds inside the paint forming a inhibiting surface-layer. Inhibitor effect. Pigments in used to achieve the inhibitor effect are often basic or water soluble, such may be various zinc derivates.
MathiasTMathiasT
$\begingroup$ Thanks, this helps a lot. But, in line with my question, it leaves me wondering things like how long it takes for enough oxygen (or calcium) to get through your best paint to cause significant weakening of the steel. But, this is a function of at least (1) paint technique including number of applied coats, (2) temperature and temperature cycling, (3) humidity, and (4) saltwater exposure. If you just quantified this effect roughly for the San Francisco area, I'd probably mark this as the answer, but I know that alone is difficult. $\endgroup$
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Madhath N. Ali received her Juris Doctor, with honors, from the Michigan State University College of Law in 2015. She earned her Bachelor of Arts in Criminal Justice at Michigan State University in 2012.
Madhath N. Ali is a member of the State Bar of California and the Orange County Bar Association.
Since 2015, Ms. Ali has defended employers, insurance carriers, and third-party administrators against workers' compensation claims. She is an aggressive, detail-oriented advocate for her clients while offering personalized customer service specific to each client's needs and expectations. She has extensive experience at Workers' Compensation Appeals Boards throughout Southern California.
After concluding two years at a workers' compensation defense firm in Orange County, she joined the Long Beach office of Dietz, Gilmor & Chazen in 2017. In her free time, Ms. Ali enjoys reading, gardening, hiking, and exploring new restaurants.