“We will give you undeniable proofs of incredible events,” announced Robert H Jackson, America’s chief prosecutor at the Nuremberg trials of Nazi war criminals, in 1945. What followed was unprecedented: a trial in which film was used as incriminating evidence, the screen placed at the head of the courtroom where the judge would usually sit.  The meticulously assembled images that appeared on that screen were made by a team of American film-makers led by John Ford and, as Jackson warned in his opening address, they made for difficult viewing. “Our proof will be disgusting and you will say I have robbed you of your sleep. But these are the things which have turned the stomach of the world and set every civilised hand against Nazi Germany.”  Within the context of an ambitious exhibition at the Photographers’ Gallery in London, Burden of Proof: The Construction of Visual Evidence, the film is doubly illuminating not only for what it shows, but for the ways in which the filmed evidence was created and presented. The filmmakers followed a set of specific instructions – “several photos should be taken of each body”, for instance, and they had to be taken “as close as possible” in order to “show, within the limits of the photograph, the entire body”. Alongside each image, detailed information had to be provided about the location, date, quality of film stock used and a written description of what had been filmed. For an image, whether moving or still, to work as evidence at Nuremberg, it needed to be forensic in descriptions of detail and context.  Related: ‘They were torturing to kill’: inside Syria’s death machine | Garance le Caisne  Burden of Proof is itself a forensic delineation of how photography has been used as evidence of war crimes and acts of violence against groups and individuals. In a way, it is not a photography show per se, more an investigation of the way in which photography has, almost since its inception, been used by experts in other fields: war crimes investigators, police forensic teams, scientists, historians, agents of the state and citizens campaigning for justice. It is a show that demands – and repays – attentiveness and a degree of steeliness, given that the photographic evidence on display includes often graphic still images and film footage as well as projections that catalogue the victims of state-sponsored purges, the uncovering of mass graves, as well as the effects of aerial bombardments and drone strikes.  It begins with the French police officer Alphonse Bertillon’s pioneering approach to crime-scene evidence, first used in 1903. Bertillon is now regarded as the inventor of “anthropometric description”, which entailed shooting the scene on a large overhead camera with a wide-angled lens and then presenting the images alongside an index of exact measurements that allowed the scene to be recreated in detail for police investigators, judges and jurors.  It is interesting to contrast Bertillon’s widescreen approach with that of his contemporary, the German-Swiss criminologist Rudolphe A Reiss, who homed in on specific details in a crime scene, objects or traces left by the criminal – fingerprints, tools, weapons (including a handkerchief used to strangle someone), and bloodstains – all of which he isolated and photographed against neutral backgrounds. Reiss, a chemist by trade, understood that photography could capture and preserve what the human eye was often incapable of seeing, calling it “humanity’s artificial memory”. The neutrality of his images is reminiscent of modernist art photography and brings to mind Irving Penn’s studies of discarded cigarette packets and butts.  The haunting, cumulative power of individual images is repeated with portraits of victims of the Great Terror in the USSR in the 1930s. Each of the accused, having often been tortured into confessing to thought crimes against the regime, were photographed in front and profile views before being executed. Their names were then written on to the negative or print for easy identification. At the height of the terror, around 50,000 executions a month were carried out, leaving behind a chilling record of systematic mass murder.  Throughout the exhibition, curator Diane Dufour has chosen photographic evidence that identifies not only the dead, but their killers. Another filmed projection illustrates how Richard Helmer, a German pathologist and photographer, deployed his pioneering videographic technique – a video image of a photograph of a human face, placed over a video image of a skull – to determine “to the closest millimetre” that a corpse found in Sao Paolo in 1984 was that of Josef Mengele, the “executioner of Auschwitz”.  More recently, photographic evidence has been used to document attacks on civilian populations. The Gaza Book of Destruction, subtitled A Verification of Building-Destruction Resulting from Attacks by the Israeli Occupation, is a people’s archive in which every building destroyed or damaged has been chronicled. Though the images are often amateurish, they present a catalogue of destruction on a scale that even oral testimony cannot hope to equal. Like the portraits from the Great Terror, each photograph contains a catalogue number referencing the location by sector, neighbourhood, road and plot, but here the numbers were painted on to the building before the photograph was taken. An attendant written record describes the size, type and use of each building as well as the number of residents and whether it was destroyed by air or ground missile attack or armoured bulldozer.  In the past few years, the multidisciplinary body Forensic Architecture, whose investigations have provided evidence for international prosecution teams, NGOs and the United Nations,has turned its attention to drone strikes. Its video A Drone Strike in Miranshah remodels a deadly attack on 30 March 2012 in Waziristan, Pakistan, in which four people were killed. (You can see a version of it here under the heading Case Study 3.) The footage begins with a small hole in a roof left by the issile designed to do minimal damage to a building while killing its occupants.  It is an illuminating example of how the United States military has turned technology on its head in the interests of state secrecy. The director of Forensic Architecture, Eyal Weizman, points out that evidence of the effects of drone strikes is denied to us. “In their real optical and digital resolution, satellite images are available only to state agencies and the specifications are secret.”  Thus, he continues, “one of the foundational principles of forensics since the 19th century has been inverted: to resolve a crime the police should be able to see more, use better optics, than the perpetrator of the crime. Here, it is the state agencies that do the killing and the independent organisations the forensics. The differential in visual capacity to see is the space of denial.”  We may have come a long way since Alphonse Bertillon’s pioneering use of metric photography, but one wonders what he would have made of our current state of secrecy and denial. For today, state-of-the-art image-making technology is used in the concealment, as well as the uncovering, of evidence.  • Burden of Proof: The Construction of Visual Evidence, is at the Photographer’s Gallery, London W1, until 10 January.
From Joseph Mengele’s skull to Gaza’s bombed-out buildings, a new exhibition presents a visual record of acts of violence in chilling detail