One interrogator had to be removed, Dunleavy said, after the interrogator "physically mishandled" a detainee, belting and handcuffing him to an eyebolt on the floor. An FBI agent was removed after "he went across the desk at a detainee" after the detainee threatened to kill his family, Dunleavy said.

Dunleavy said his "best interrogator" was prosecuted and that another officer was removed after it became apparent he was an alcoholic who secretly drank in his room every night.

Loud music and yelling were used to disrupt detainees' thought process, Dunleavy said. Chaining a detainee in a fetal position was "not a normal procedure," he said, but may have been used to secure a prisoner who leapt at an interrogator.

Maj. Gen. Geoffrey Miller, who commanded Guantanamo from late 2002 to March 2004, said in another newly released document that he had rejected a proposal to use the harsh techniques employed by survival trainers to prepare American troops for combat. He said some of the techniques "went beyond what I felt comfortable with."

Some of the same harsh techniques had already been secretly adopted by the CIA with White House approval.

Another set of memos, dated 2004, described how a detainee was knocked unconscious for several minutes by guards while he was being forcibly removed from his cell.

The memos were apparently written in response to State Department inquiries about a prisoner's treatment at the military run jail.

"Please assure (redacted) that their detainees have never been subjected to torture or systematic abuse," wrote Matthew Waxman, then the director of detainee affairs for the Pentagon, in an October 2004 memo to an undisclosed recipient. "Additionally, while he has some mental health issues, these are not the result of any physical abuse at Guantanamo."

Waxman did not mention in that letter that the detainee had been knocked unconscious. The detainee's identity was redacted from the memo.

In another memo, a Marine officer recommended an investigation into a report by "one of the most, if not the most, cooperative and influential detainees" at Guantanamo, who alleged he was tortured at the facility between August and October 2003 by methods involving women, sleep deprivation and exposure to cold.

Most of the details of the detainee's account were blacked out. But he said he once was forced to stay awake for 70 days, that interrogators put ice all over his body directly against his skin inside his clothes, and that there was a room that the detainees called the "freezer." He said he made a false confession while being tortured.

Another document detailed "troubling" interrogation techniques used against the detainee during that period, including a threat that if he didn't talk he would "soon disappear down a very dark hole" and that his "very existence would be erased."

The same document, undated, noted that at the time 40 percent of the abuse allegations in Iraq were being substantiated by investigations.