Despite intense efforts to keep most of the details of their use of torture secret over recent years, the CIA’s most recent release of documents included several which shed new light on the practice of torture, as well as underscoring an intense internal debate within the agency about the policy.

Among these were cables about the torture of Abu Zubaydah, revealing he was waterboarded 83 different times in a single month, and kept in a small box to small for him to sit up in for hours on end to induce pain. It also revealed there was a formal policy of smacking him repeatedly head-first into walls, with torturers admonished to put a rolled up towel behind his neck to prevent permanent neck injuries.

The Zubaydah memos are all very clinical, saying things like “water treatment was applied” and that he didn’t offer any new intelligence, before concluding after weeks of vicious abuse that he had not provided “significant actionable intelligence” beyond what they got pre-torture, and that he probably didn’t have anything new to give them.

All of this torture was ongoing under the oversight of a pair of contracted psychologists, James Mitchell and J. Bruce Jessen, who are now facing a lawsuit over their designing of the torture program. CIA officials weren’t nearly as unanimous in supporting the program as they’ve been presented by some, however.

Other documents show internal emails from the CIA’s own medical staff warning that the behavior was indefensible, and that the two contractors showed a “blatant disregard for ethics” in their operation of the program. They also reveal a faction battle between the CIA Counterterrorism Center, which contracted the two men, and the Office of Medical Services, who warned the techniques proposed would “come back to haunt us.”

The collection also grimly includes accounts of the final hours of Gul Rahman, a detainee who died in CIA custody in 2002, with Jessen arguing that Rahman was so physically strong that there would be no way to “break” him while respecting the Geneva Convention.

Since that apparently was no obstacle, Rahman had a hood put over his head and was dragged out of his cell and beaten, which they deccided was “nothing that required treatment.” He was then doused with water and left in a freezing cold sell called the Salt Pit. This is followed by prison records of guards checking Rahman every night to see if he was still alive, and a single entry at the end concluding that he’d finally died.