The documents, internal reports from more than 50 criminal investigations, further refute government claims last year that photographs from Abu Ghraib showed isolated pranks of a few low-ranking soldiers.
The records include new allegations of forced sodomy, the use of dogs to frighten detainees and severe beatings of hooded and handcuffed prisoners. In one case, investigators determined that a commander and three members of an Army Special Forces unit - none of whom was publicly identified - had committed murder by luring an Afghan civilian to a roadblock before detaining him and shooting him.
No court-martial was convened in the case, according to the records released yesterday. Only one soldier was punished, receiving a written reprimand.
In another case, a soldier told investigators: "I saw what I think were war crimes on the people of Iraq." But in closing the case, agents with the Army Criminal Investigation Command said there was "insufficient evidence to prove or disprove" the claims from the Camp Red detention facility in Baghdad - a finding repeated often in the investigative files.
An Army spokesman said last night that the files released yesterday, many of them heavily redacted, do not give the full picture of how seriously the military has responded to allegations of detainee abuse.
"The Army has aggressively investigated all credible allegations of detainee abuse and held soldiers accountable for their actions," Army spokesman Dov Schwartz said. "There have already been several major inquiries examining all aspects of detainee operations; additional inquiries are under way. ... The Army's record of investigating detainee abuse continues to be thorough and fair."
He said there have been more than 300 criminal investigations and more than 100 personnel have faced penalties through courts-martial, nonjudicial punishment or administrative action.
ACLU Executive Director Anthony D. Romero said the investigative records released by the government so far - obtained through the organization's continuing lawsuit under the Freedom of Information Act - show a pattern of "woefully inadequate" investigations.
Amrit Singh, an ACLU staff attorney who has worked closely on the lawsuit, said that in some cases, "investigations were abandoned before relevant witnesses were questioned."
In other cases, she said, investigations were dropped because the abuses were considered "standard operating procedure."
The soldier at Camp Red, for instance, told investigators that "a lot of pictures were taken," some showing the "mistreatment or crimes against the people that were caught."
"Sometimes there would be prisoner's [sic] with sand bags on their heads, standing on a brick with their hands behind their head, and concertina wire all around them," the soldier said about detainee treatment at the facility in November 2003, roughly the same time the worst abuses took place at Abu Ghraib. "If they got off the brick they were manhandled."
For the past year, criminal charges in the detainee abuse scandal have been tightly focused on seven low-ranking members of the 372nd Military Police Company, an Army Reserve unit from Western Maryland whose soldiers served as guards at the Abu Ghraib prison in fall 2003.
Three soldiers from the unit have pleaded guilty. Spc. Charles A. Graner Jr. was convicted and sentenced to 10 years at a military trial this month after prosecutors presented a case that focused mainly on the events of a single night at the Baghdad prison.
But government records and a series of Pentagon reports have portrayed the abuses as more widespread, reaching to detainee camps in Afghanistan and to the U.S. detention facility at Guantanamo Bay, Cuba.
In a statement yesterday, military officials acknowledged for the first time that 23 terror suspects held at Guantanamo Bay in 2003 tried to hang or strangle themselves in a mass protest.
The investigative files released by the ACLU had other new details about U.S. detention operations in Iraq and Afghanistan. The documents show that investigators received numerous reports of detainee mistreatment at the Al-Azimiyah Palace in Baghdad, including one from a U.S. civilian contractor who said at least 90 incidents of abuse occurred there.