Sleep deprivation, beatings, shackling and waterboarding are among the methods used by the CIA to interrogate al-Qaeda terror suspects.
Slaps and 'wallings'
Beginning with the CIA's first high-value al-Qaeda detainee Abu Zubaydah, suspects were routinely slammed against a wall by their interrogators and hit with rolled-up towels. Facial slaps, or "insults," as well as stomach punches were also used.
The interrogators also used "attention grasps" in which the prisoner is grabbed with both hands, one on each side of the collar and pulled towards the interrogator.
This involved keeping detainees awake for up to 180 hours, or more than a week, usually standing or in stress positions, sometimes with their hands shackled above their heads, chained to the ceiling. Abu Zubaydah was kept in an all-white room that was lit 24 hours a day. Or he was kept awake by non-stop questioning.
At least five detainees suffered "disturbing hallucinations" but in at least two cases the CIA continued with the interrogation method.
Confinement and isolation
Over 20 days, Abu Zubaydah spent 266 hours (11 days, 2 hours) in a large coffin-size box, and 29 hours in an even smaller one. In the Cobalt facility, prisoners were kept in complete darkness, often shackled with their hands above their heads and mainly nude.
They were bombarded with loud music and noise and given a bucket as a toilet. In 2002 a prisoner who had been partially nude and chained to a concrete floor died of suspected hypothermia. Ice water baths or showers were also used to try to break suspects.
Some detainees were also forced to wear nappies, although guidelines said they could not be left on longer than 72 hours.
This was used at the Cobalt facility. About five CIA agents would scream at a detainee, drag him outside his cell, cut his clothes off and wrap him in duct tape. He would then be hooded and dragged up and down a dirt hallway while being slapped and punched.
After his death at the COBALT site, Gul Rahman was found to have been covered with bruises and abrasions on his shoulders, pelvis, arms, legs and face.
Prisoners were often stripped and left nude in their cells. Zubaydah was kept naked but given a towel to cover himself during interrogations.
Abd al-Rahim al-Nashiri, the alleged mastermind of the 2000 attack on the USS Cole, was often naked during his grillings. But at one point he was given clothes when he was racked by shivering because of a head-cold.
CIA officers regularly threatened the detainees. One was told he would only leave the facility in "a coffin-shaped box". At least three detainees were told the CIA would hurt their families, including their children. There was a threat to sexually abuse the mother of one, while another was told his mother's throat would be cut. The methods were supposed to ensure prisoners developed a sense of "learned helplessness".
Forced rectal feeding
At least five prisoners were subjected to "rectal rehydration or rectal feeding without documented medical necessity". Other detainees were given a liquid diet of protein drinks called Ensure "as a means of limiting vomiting during waterboarding".
In this technique of "near drownings", the detainee was bound to an inclined bench with his feet usually raised. A cloth is placed over the forehead and eyes, and water is then poured in a controlled way on to the cloth, which is then lowered over the nose and mouth. Once the cloth is saturated, the prisoner's flow of air is restricted for up to 40 seconds while the cloth is left in place over the nose and mouth.
The self-confessed mastermind of the 9/11 attacks, Khalid Sheikh Mohammed, is known to have been waterboarded 183 times.