For an elite unit with roughly 1,000 people at any given time, Task Force 6-26 seems to have had a large number of troops punished for detainee abuse. Since 2003, 34 task force members have been disciplined in some form for mistreating prisoners, and at least 11 members have been removed from the unit, according to new figures the Special Operations Command provided in response to questions from The New York Times. Five Army Rangers in the unit were convicted three months ago for kicking and punching three detainees in September 2005.

Some of the serious accusations against Task Force 6-26 have been reported over the past 16 months by news organizations including NBC, The Washington Post and The Times. Many details emerged in hundreds of pages of documents released under a Freedom of Information Act request by the American Civil Liberties Union. But taken together for the first time, the declassified documents and interviews with more than a dozen military and civilian Defense Department and other federal personnel provide the most detailed portrait yet of the secret camp and the inner workings of the clandestine unit.

The documents and interviews also reflect a culture clash between the free-wheeling military commandos and the more cautious Pentagon civilians working with them that escalated to a tense confrontation. At one point, one of Defense Secretary Donald H. Rumsfeld's top aides, Stephen A. Cambone, ordered a subordinate to "get to the bottom" of any misconduct.

Most of the people interviewed for this article were midlevel civilian and military Defense Department personnel who worked with Task Force 6-26 and said they witnessed abuses, or who were briefed on its operations over the past three years.

Many were initially reluctant to discuss Task Force 6-26 because its missions are classified. But when pressed repeatedly by reporters who contacted them, they agreed to speak about their experiences and observations out of what they said was anger and disgust over the unit's treatment of detainees and the failure of task force commanders to punish misconduct more aggressively. The critics said the harsh interrogations yielded little information to help capture insurgents or save American lives.

Virtually all of those who agreed to speak are career government employees, many with previous military service, and they were granted anonymity to encourage them to speak candidly without fear of retribution from the Pentagon. Many of their complaints are supported by declassified military documents and e-mail messages from F.B.I. agents who worked regularly with the task force in Iraq.

A Demand for Intelligence

Military officials say there may have been extenuating circumstances for some of the harsh treatment at Camp Nama and its field stations in other parts of Iraq. By the spring of 2004, the demand on interrogators for intelligence was growing to help combat the increasingly numerous and deadly insurgent attacks.