"In the immediate aftermath of 9/11 we did some things that were wrong. We did a whole lot of things that were right, but we tortured some folks."
It's been more than a year since US President Barack Obama admitted that the CIA tortured prisoners at its interrogation centres.
While the CIA has long admitted the use of waterboarding, which simulates drowning by pouring water into a person's nose and mouth, a truncated and heavily redacted report by the Senate Intelligence Committee in December 2015 detailed other abuses that went beyond previous disclosures.
Reading like a script from a horror film, some of the techniques involved prisoners being slapped and punched while being dragged naked up and down corridors, being kept in isolation in total darkness, subject to constant deafening music, rectal rehydration and being locked in coffin-shaped boxes.
Critical to the development of the CIA's brutal interrogation programme was a legal memo that said the proposed methods of interrogation were not torture if they did not cause "organ failure, death or permanent damage".
READ MORE: The dark prisoners - Inside the CIA's torture programme
Despite failing to produce any useful information about imminent terrorist attacks, the CIA meted out these and other brutal treatments for years after the September 11, 2001 attacks.
And with dozens of people having since been released without charge, and at least a quarter of them officially declared to have been "wrongfully detained", the effects of torture live on with the victims, burned into their minds.
In this 50-minute Fault Lines special, we expand on our original film The Dark Prison, exploring the plight of the men struggling to overcome their harrowing experiences of torture since leaving CIA-run black sites.
Watch the original film The Dark Prison here:
Source: Al Jazeera