The results of an Army probe of the photographs were among hundreds of pages of documents released after the ACLU obtained a federal court order in Manhattan to let it see documents about U.S. treatment of detainees around the world.
The ACLU said the probe shows the rippling effect of the Abu Ghraib scandal and that efforts to humiliate the enemy might have been more widespread than thought.
"It's increasingly clear that members of the military were aware of the allegations of torture and that efforts were taken to erase evidence, to shut down investigations and to humiliate the detainees in an effort to silence them," ACLU Executive Director Anthony Romero said.
The Army did not immediately return a telephone message seeking comment.
The probe of the pictures in Afghanistan began after a CD found there during a July office cleanup contained pictures of uniformed soldiers pointing guns at bound and hooded detainees.
The investigation showed that the pictures were taken in and around Fire Base Tycze in southern Afghanistan, according to the documents, which blacked out the identities of those interviewed.
An Army specialist told investigators that similar photographs were destroyed after images of torture at Abu Ghraib were leaked to the media.
Another Army specialist admitted he was photographed standing behind a prisoner while holding a weapon to his head, according to the released records. The specialist told investigators he considered those kinds of pictures bad because they would enrage the public.
The probe established probable cause to believe eight soldiers committed dereliction of duty when they jokingly pointed weapons at bound detainees and took pictures, the Army records show.
Earlier documents released by the ACLU had primarily been from the FBI. The ACLU also is seeking documents from the CIA and the Department of Defense.
Other Army documents released Friday outlined the case of an Iraqi detainee who said Americans in civilian clothes beat him, dislocated his arms, fired an unloaded pistol into his mouth and beat his leg with a bat before making him denounce his abuse claims to win release. A criminal file on the alleged abuse was closed because the probe could not prove or disprove the claims.
The Army documents also describe a probe into complaints by senior psychological operations officers in Afghanistan that they saw assaults by special forces on civilians during raids in May 2004 in the villages of Gurjay and Sukhagen.
That investigation was suspended because the victims could not be interviewed and prospective witnesses were enemy forces, the Army said in its documents.
By Larry Neumeister