August 7, 2008
Forensic Specialists Work Wonders With Fingerprints
Scientists have developed new ways to retrieve even more information from fingerprints, resulting in better chances for forensic researchers to solve mysteries like the anthrax attacks or JonBenet Ramsey's murder.
Chemist R. Graham Cooks of Purdue University in West Lafayette, said one example might be if a person handled cocaine, explosives or other materials, there could be enough left in a fingerprint to identify them.Max M. Houck, director of West Virginia University's Forensic Science Initiative, said progress in forensics comes from a combination of new techniques, like those involved in the anthrax investigation, and existing techniques, like those used in the Ramsey case.
The FBI revealed this week that improvements in genetic research allowed police to trace the anthrax used in the 2001 attacks to a specific flask of spores.
And while the killing of 6-year-old Ramsey attracted national fascination in 1996, it was only this year that prosecutors announced that a new series of tests pointed to an unidentified attacker, clearing family members of suspicion.
Houck said the testing technique in Ramsey's case was not new. But prosecutors learned it could be relevant to their case in a 2007 West Virginia University course.
Cook noted that in the new fingerprint analysis method, police technicians armed with miniaturized mass spectrometers can spray a solvent on a fingerprint and detect compounds at concentrations as fine as five parts per million in droplets that scatter off the print. Five parts per million is equivalent to five ounces of chemical in 32 tons of material.
He said he testing method, discussed in Friday's edition of the journal Science, could be available in a year or two.
Cook explained that materials such as cocaine and military explosives tend to be hard to get off the fingers. If someone who has handled them later handles something hard like a file or plastic binder, that will transfer the chemicals, he said.
The chemicals are located at the points of the fingerprint's ridges, so what is then on the hard surface is the fingerprint in chemical. So police can not only identify the person from the print, but also connect the person and the drug or chemical, he said.
The technology also can uncover fingerprints buried beneath others, according to co-author and Purdue researcher Demian R. Ifa.
"Because the distribution of compounds found in each fingerprint can be unique, we also can use this technology to pull one fingerprint out from beneath layers of other fingerprints," Ifa said.
"By looking for compounds we know to be present in a certain fingerprint, we can separate it from the others and obtain a crystal clear image of that fingerprint."
Radiocarbon dating, something most people associated with determining the age of ancient things like dinosaurs, is another method that can be used. But the atomic bomb tests in the 1950s have provided a method for more recent testing by disrupting the previously uniform levels of carbon-14 in the atmosphere.
"That introduced huge amounts of radioactive carbon into the atmosphere, and subsequently us," explained Douglas Ubelaker, a forensic anthropologist at the Smithsonian's National Museum of Natural History.
"With the increase in radioactive carbon during the tests and its decline after testing was stopped, researchers were able to develop a "bomb curve" for the amount that might be found in the body of an individual," said Ubelaker.
Ubelaker said body cells are continually being replaced - faster in soft tissues, more slowly in bones and teeth - and comparing the ratios allows for the estimation of someone's date of death and, possibly, their date of birth.
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