Taguba testified that only "a few" soldiers and civilians at the Abu Ghurayb prison outside Baghdad were responsible for the abuse, which included threats and sexual humiliation. He said the mistreatment, which is documented in photographs, is forbidden by U.S. and international law.
The blame for the acts themselves lies with the lower-ranking officers, according to Taguba. He said his investigation found no evidence that senior officers ordered them to abuse the prisoners.
"We did not gain any evidence where it was an overall military-intelligence policy of this sort. I think it was a matter of soldiers with their interaction with military-intelligence personnel who they perceived or thought to be competent authority that were giving them -- or influencing their action to set the conditions for successful interrogations operations," Taguba said.
Assessing blame at the hearing hinged on who was in control of Abu Ghurayb at the time the abuse occurred in 2003. Taguba said Colonel Thomas Pappas, a military-intelligence officer, had been put in charge of the prison, and therefore Pappas's unit bore responsibility.
But another witness at the hearing, Stephen Cambone, the U.S. undersecretary for intelligence, said Pappas was given control over only intelligence gathering at the prison, not the operation of the prison itself.
"I do not believe that the order placing Colonel Pappas in charge gave him the authority to address the MPs' [military police's] activities in direct op-con [operational-control] conditions," Cambone said.
Therefore, Cambone said, the responsibility for the abuse still lay with the military police, who had been staffing the prison since Saddam Hussein was ousted as Iraq's president more than a year ago.
Taguba also said U.S. Army rules forbid military-intelligence officials to enlist the help of military police in preparing detainees for interrogation. He said that he found no evidence of any order directing the military police to help the interrogators.
Again Cambone disagreed, saying it was appropriate for the two to work together.
But both men agreed that there had been at least some involvement of the U.S. Central Intelligence Agency (CIA) in the mistreatment of Iraqis at Abu Ghurayb.
U.S. Defense Secretary Donald Rumsfeld appeared before the committee on 7 May, and, on the same day, before its sister committee in the House of Representatives. Rumsfeld testified that there are many other photographs, and some videos, of the abuse that have not yet been made public.
The leaders of the Senate are trying to get access to these photos and videos to help determine the extent of the abuse. If access is granted, senators would be permitted to view the photos only in a secure room in the Capitol building to prevent leaks that could violate the victims' privacy or hamper the prosecution of those charged in the case.
So far, seven low-ranking military personnel have been charged, and one will face a court-martial beginning on 19 May. Six officers and noncommissioned officers have been issued letters of reprimand for their suspected roles in the abuse.