The public image of detainees in Iraq was defined by the photographs, now infamous, of American abuse at Abu Ghraib, like the hooded prisoner and the snarling attack dog. While the documents disclosed by WikiLeaks offer few glimpses of what was happening inside American detention facilities, they do contain indelible details of abuse carried out by Iraq’s army and police.

The six years of reports include references to the deaths of at least six prisoners in Iraqi custody, most of them in recent years. Beatings, burnings and lashings surfaced in hundreds of reports, giving the impression that such treatment was not an exception. In one case, Americans suspected Iraqi Army officers of cutting off a detainee’s fingers and burning him with acid. Two other cases produced accounts of the executions of bound detainees.

And while some abuse cases were investigated by the Americans, most noted in the archive seemed to have been ignored, with the equivalent of an institutional shrug: soldiers told their officers and asked the Iraqis to investigate.

A Pentagon spokesman said American policy on detainee abuse “is and has always been consistent with law and customary international practice.” Current rules, he said, require forces to immediately report abuse; if it was perpetrated by Iraqis, then Iraqi authorities are responsible for investigating.

That policy was made official in a report dated May 16, 2005, saying that if “if US forces were not involved in the detainee abuse, no further investigation will be conducted until directed by HHQ.” In many cases, the order appeared to allow American soldiers to turn a blind eye to abuse of Iraqis on Iraqis.

Even when Americans found abuse and reported it, Iraqis often did not act. One report said a police chief refused to file charges “as long as the abuse produced no marks.” Another police chief told military inspectors that his officers engaged in abuse “and supported it as a method of conducting investigations.”

It is a frightening portrait of violence by any standards, but particularly disturbing because Iraq’s army and police are central to President Obama’s plan to draw down American troops in Iraq. Iraqi forces are already the backbone of security in Iraq, now that American combat troops are officially gone, and are also in charge of running its prisons.

The archive contains extensive, often rambling accounts of American abuse from Iraqi prisoners, but few were substantiated. The most serious came during arrests, which were often violent when people resisted. In those cases, investigations were opened. In a case reminiscent of Abu Ghraib, in which guards photographed themselves with Iraqis whom they had posed in humiliating positions, a soldier was censured for writing a mocking slur with a marker on the forehead of a crying detainee.