Image: still taken from Forensic Architecture video 'Rafah - Bomb Identification'. Full video below.

Thresholds of Detectability and Investigative Aesthetics

The state, via the police and criminal justice system, is normally responsible for the investigating the crimes of individuals.  But what happens when the state is the alleged criminal and those seeking to uncover crime are operating under conditions of structural inequality regarding access to evidence?  In recent years the Forensic Architecture Agency has begun to use a range of diverse and novel methods to investigate human rights abuses, and this is the subject of an exhibition at the Museu D’Art Contemporani de Barcelona and a new book on the topic by Eyal Weizman.

Forensic Architecture scrutinises the production of public truth using new media, remote sensing, material investigation and witness testimony.  Both the exhibition and book begin by revisiting the bizarre libel case, fought out in the English High Court in 2000, between Holocaust denier David Irving and American historian, Deborah Lipstadt.   Irving filed a libel suit against Lipstadt, and her publisher, for calling him a ‘falsifier of history’.  The legal debate in the trial fixed on the architecture of the gas chamber associated with Crematorium II in Auschwitz-Birkenau – a 200 square meter space in which ‘approximately half a million people were killed’.   Irving focused his case on four small holes in the roof of this partially destroyed structure and claimed that there was no evidence that these holes ever existed.  It was through these apertures that the Zyklon B was poured to murder those in the chamber below.  Irving’s logic was that without the holes Zyklon B could not be introduced into the room, and it, therefore, could not be a gas chamber.  If it was not a gas chamber, then Auschwitz was not an extermination camp, and therefore the racially motivated killing of the Holocaust did not happen.  “No holes, no Holocaust”, no falsification of history.

Image: Displayed at Forensic Architecture exhibition, MACBA, taken from ‘Images in Spite of All’ by Georges Didi-Huberman 2008

This is a tactic commonly used to refute the testimonies of survivors of violence: referring to material evidence, or more precisely the lack of material evidence.  It is a tactic that can be particularly effective where history or geopolitical barriers make access to a crime scene difficult.  “Posing matter against memory… seemed to advocate a history without witness and beyond language”.  Yet material evidence for the existence of the holes and the industrial production of mass murder was available and presented by architectural historian Robert Jan van Pelt.  These included diaries, logbooks, architect’s drawings and photographs.  Central to this evidence was a US Air Force reconnaissance photograph taken in August 1944 and reanalysed by the CIA in 1978.

Image: Displayed at Forensic Architecture exhibition, MACBA, ‘Images of the World and the Inscription of War’ by Harun Farocki, 1988. The pattern interruption on the image of the vents is a result of printing.

The images showed what appeared to be openings in the roof the building (described as vents), yet Irving claimed that these photographs were inauthentic and contained ‘brush strokes’ added after the photos were taken.  However, testimony given by Nevin Bryant, a NASA expert in the analysis of aerial images, explained that the brush strokes were in fact interference patterns caused by the photographic process.  The images of the roof openings were taken at the very limits of the film’s resolution for capturing objects of this size (0.5m2) from an altitude of 15,000 feet.

The evidence of van Pelt and Bryant ensured that Irving lost the trial and he was described by the judge as a racist anti-Semite who “for his own ideological reasons persistently and deliberately misrepresented and manipulated historical evidence”.  But the trial demonstrated the importance of the “threshold of detectability” and the tension between testimony and evidence that are so important to Forensic Architecture:

The forensic condition of ‘the threshold of detectability’ is central to our understanding of the challenges and limitations of our practice. It occurs when the size of an object recorded on the ground is close to the size of the element that records it on the image – a single silver salt grain, or a pixel. In this condition things hover between being identifiable and not.  At the threshold of detectability, both the surface of the image and that of the thing it represents must be studied as both material object and as media, simultaneously both presence and representation.

Forensic Architecture and Aesthetic Practice

That evidence can be both material object and media, presence and representation bring forth the idea that forensics is also an aesthetic practice because “it rests on the modes and means by which reality is sensed” and how it gets presented back in public venues.  These issues were of crucial importance when Forensic Architecture investigated Western drone warfare as conducted in Pakistan, Afghanistan, Yemen, Somalia and Gaza.  Here a key change had happened in the way that drone warfare was conducted: a move from targeting vehicles to targeting buildings.  Drone strikes on buildings used a modified Hellfire missile with a delayed fuse.  The allowed the missile to break through several layers of roof or wall before exploding deep within a building with a payload of steel fragments designed to rip through flesh but leave a building structure largely undamaged.  The only external evidence of a drone strike is often merely a small hole in the roof or wall of a building.

By their very nature, regions, where drone strikes are used, tend to be inaccessible to human rights investigators.  But one possible way to scrutinise these strikes would be to use satellite imagery.  However, publicly available satellite imagery is restricted to 0.5 meters per pixel, a restriction that does not apply to the military users of satellite and drone imagery to aid their targeting.  Just as with the photographs of Auschwitz, the hole in a roof “indicated that the room under it was an execution chamber, and in both cases, such holes and the violence they evidenced were at the threshold of detectability”.  This gives rise to another inversion.  In most cases of criminal investigation, it is the police who have better access to forensic data than the criminals.  However, in these cases ‘it is the killer who has access to better optics, data and information than the investigators’.  In these cases, Forensic Architecture must cross-reference multiple other evidence sources.  For instance, on March 20 2012, a drone struck a building in a market area of Miranshah in Pakistan killing four people.  The area was under strict military control that prevented the transit of electronic media.  However, a 43-second video was smuggled out that allowed the room where the drone exploded to be reconstructed.  In the image below the areas with fewer shrapnel lines are the likely places where bodies absorbed the fragments.  Such reconstructions make the denials of Pakistani and US spokespersons, about a covert drone campaign, more difficult to maintain.

Image: Full-scale reconstruction displayed at Forensic Architecture exhibition, MACBA, of targeted room in which blast occurred


Image: Displayed at Forensic Architecture exhibition, MACBA, of missile egress through a building and eventual blast delivering lethal steel fragments.

Similarly, after the most destructive day of the 2014 Gaza war, Forensic Architecture and Amnesty International were denied entry by the Israeli Government to the strip.  So, their investigation relied on thousands of images and videos posted online.  These were painstakingly reconstructed into a narrative by studying ‘physical clocks’ such as shadows and bomb clouds.  In this way, each image was located in time and place to ‘compose a narrative of these fatal 24 hours’.

Forensic Architecture has conducted similar investigations into state violence in Syria, the killings of Palestinian teenagers in Beitunia, environmental crime in Indonesia, and the ‘left to die’ migrants in the Mediterranean.  These new methods and practices used to investigate violence and human rights abuses, arrive at a time when state denial, obfuscation and propaganda are on the rise.   In a world on the precipice of a new and dangerous ‘post truth’ politics, Forensic Architecture’s use of contemporary aesthetic practices and media technologies offers an innovative empirical response to counter denial and obfuscation.


The ‘Forensic Architecture – Towards an Investigative Aesthetics‘ exhibition is displayed at the Museu D’Art Contemporani de Barcelona until 15 October 2017.  

Forensic Architecture is a research agency based at Goldsmiths, University of London.  It includes a team of architects, scholars, filmmakers, designers, lawyers and scientists to undertake research that gathers and presents spatial analysis in legal and political forums.

Forensic Architecture -Violence at the Threshold of Detectability by Eyal Weizman (2017), Zone Books: New York