How do we know things? - The Investigator’s Dilemma and Working with Absent Evidence

“Do we know things? How do we know them? Philosophers have been asking these questions for thousands of years. But for investigators and researchers, they have a particular resonance. What do we do when we investigate? How do we derive meaning from data and the absence of data?” (Crofton Black*). - In this brief article we look at one investigative project that used creative means and plenty of collaboration to draw meaning from absent information in order to expose a global operation of rendition and secret detentions conducted by the CIA.

This article provides a snapshot from Crofton Black's talk on “Investigation Philosophies” at the Investigation is Collaboration conference organised by Exposing the Invisible Project on 2-6 August 2021.

by Di Luong

Welcome to the dilemma that investigators face day to day: “Do we know things? How do we know them?” - Investigators deal with imperfect knowledge, they build knowledge from little bits of data and oftentimes, they build knowledge from evidence gaps, from the invisible.

In 2010 writer and investigator Crofton Black started working on uncovering operations of the CIA’s (USA Central Intelligence Agency) Eastern European secret prison sites, also called “black sites” due to the secrecy surrounding them. This research took him and an large team - including other investigators, human rights defenders, lawyers and journalists - years of meticulous and creative work.

  • Extraordinary rendition programs are highly classified, extrajudicial operations, which involve government-sponsored actions of abducting and relocating suspects from their home countries to other regions for interrogation, torture and secret detention.

The challenge the team faced seemed initially unresolvable. Firstly, they were looking into a secret (by default) global operation. Secondly, when they finally got documents that could shine some light on the grievous issue they were investigating - that is, the CIA’s post-9/11 torture program, its victims, methods and those involved - almost all the important information had been redacted, blacked out literally. They addressed the challenge primarily through seeking and finding evidence from the absence of data and by combining various methods, skills and tools that only a collaborative effort could have enabled. Their years of investigation led to successful litigation at the European Court of Human Rights and a comprehensive report - CIA Torture Unredacted - on the history of the CIA's extraordinary rendition program.

Snapshot by the author of an Extract from the Committee Study, with dates, CIA officers and cable data redacted, and with PSEUDONYMS for black sites and contractors; page 24; “CIA Torture Unredacted: An Investigation Into the CIA Torture Programme;” Project by The Rendition Project, The Bureau of Investigative Journalism, University of Westminster, The University of Sheffield, 2019; written by Sam Raphael, Crofton Black and Ruth Blakeley.

The team’s meticulous work produced perhaps the most detailed public account of the entire torture program led by the CIA in the time period of the so-called “war on terror” between 2001 and 2009. It is very important to read the entire report by Sam Raphael, Crofton Black and Ruth Blakeley to understand the scale, depth and extent of this program, including detailed profiles of prisoners, locations of secret sites, complex networks of private companies involved in the program and a detailed overview of apparent complicity by a number of key countries.

  • For a more complex review of this investigation and more insight into what visible and invisible traces, signs and symbols can help reveal in an investigation, read our Exposing the Invisible Kit guide Signs, Symbols and Other Visual Clues.

Crofton Black shared some lessons from this research process that took plenty of collaborative work, creativity and patience to unravel.

At the heart of this investigation was a sense of emptiness. Their team of researchers had to start with what was still visible in the otherwise heavily redacted documents in order to derive traces of prison locations from many different sources of incomplete data. This research could not include testimonies from prisoners so they relied on secondary sources from Amnesty International, inquiries in archives, flight records, financial documents gathered from Freedom Of Information Act(FOIA) requests and other sources.

Among the challenges they encountered were:

  • Heavily redacted governmental documents.
  • FOIA requests often depended on luck as some requests were successful and others were unsuccessful.
  • Disparate documents that required researchers to identify common themes - for example, synthesising flight records into one coherent flight pattern by connecting flight numbers, dates, and travel invoice numbers. None of these documents were machine readable so this information had to be manually entered to create a database.

 Some lessons learned from this investigation:

  • Learn the language and vocabulary of the ‘field’ you are researching - In this case, investigators learned to understand the overall structure of the documents through understanding communication protocols and acronyms used by those running the rendition program activities. 
  • Look for the gaps in data and make use of them when building your evidence - There were also many gaps or holes in the data the team had available. Prisoner testimonies were detailed, but contained inaccuracies and gaps. However, investigators used this to their advantage by using the absence of information as indicators. For example, investigators deduced that gaps in flight information represented prison transfers.
  • Connect the dots to meet a goal - Unlike journalistic reporting, filing a lawsuit (which is what this research was also used for) needs to prove an argument and have a focused goal. In other words, to clearly show a cause and effect from point ‘A’ to point ‘Z.’ Connecting between two points of data, investigators were able to see a pattern, and finally understood where a plane went from the flight data.
  • Believe what you see...but verify - When investigating, hypotheses don’t need to be true or probable, but must be consistent with the observations.
  • Build a bigger picture, then break it down to understand the parts - Investigators were “drowning in data” as they have collected 15 millions lines of transactions related to the rendition flights and the companies contracted to run the CIA operations across borders. It took years to synthesise the data into coherent information and ultimately into stories. It was essential for the team to create a chronology of records and find meaningful entry points into this data as well as human stories that could bring the data and the meanings behind it to a wider audience. In philosophical terms, investigators needed to understand the whole by understanding the parts.

*Crofton Black is a writer and investigator. He is co-author of Negative Publicity: Artefacts of Extraordinary Rendition and CIA Torture Unredacted, and works on technology and security topics for The Bureau of Investigative Journalism in London. Before this he was a history of philosophy academic, specialising in theories of knowledge and interpretation. He has a PhD from the Warburg Institute, London and was a Humboldt Fellow at the Freie Universität Berlin. More info at

This article is part of a series of resources and publications produced by Exposing the Invisible during a one-year project (September 2020 - August 2021) supported by the European Commission (DG CONNECT)

European Commission

This text reflects the author’s view and the Commission is not responsible for any use that may be made of the information it contains.

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