Washington ? At least five soldiers objected last fall to abuses they saw at the Abu Ghraib prison near Baghdad. One demanded to be reassigned, saying the behavior he witnessed there “made me sick to my stomach.”

Up the chain of command, the noncommissioned officers who heard such complaints did little to stop the mistreatment, according to Army records obtained by The Associated Press.

One of those same NCOs, Staff Sgt. Ivan L. “Chip” Frederick, is accused of stomping on prisoners’ toes and punching another prisoner so hard in the chest that he remarked, “I think I might have put him in cardiac arrest.” Frederick is among six soldiers facing courts-martial. Another soldier pleaded guilty last month.

The military’s full-blown investigation into beatings and humiliations at Abu Ghraib began in January, after one soldier wrote an anonymous letter to superior officers about troubling photographs. That soldier, Spc. Joe Darby, came forward later to talk to Army investigators and eventually became known as the whistle-blower who uncovered the scandal.

Internal Army documents show that others, too, condemned the abuse they saw at the prison, although their complaints failed to prevent further mistreatment.

A diminutive platoon leader, Sgt. 1st Class Shannon Snider, once barked so loudly at soldiers stomping on prisoners’ toes that one witness later told investigators, “I never thought that that voice could come out of somebody so little.” Then Snider left the room and the abuse continued, the records say.

The fact that earlier complaints apparently went nowhere adds to the uncertainty over a key question in the Abu Grhaib scandal: Did superior military police or intelligence officers encourage or condone the abuses?

A report from Army Maj. Gen. Antonio Taguba says yes. Taguba wrote that commanders of both the military police and intelligence troops at the prison knew or should have known about the abuse. His report also says military intelligence officers unsuccessfully pressured one military dog handler to sic his animal on prisoners.

In this undated photo made available Friday by The Washington Post, an unmuzzled dog faces a naked Iraqi detainee at Abu Ghraib prison in Baghdad. Two military dog handlers told investigators that US intelligence personnel ordered the use of dogs to intimidate prisoners. At least five soldiers complained about prisoner treatment last fall, but their complaints were largely ignored.