In one shot a body bag has been opened to show the gruesome head wound of the corpse. In another, a G.I. is leaning over the top of the body bag with a spoon in his right hand, as if he is about to scoop up a portion of the dead man's wounded flesh.

"These pictures were circulated like trophies," Mr. Delgado said.

Some were posted in command headquarters. He said it seemed to him that the shooting of the prisoners and the circulation of the photos were viewed by enlisted personnel and at least some officers as acceptable -- even admirable -- behavior.

Mr. Delgado said that when his unit was first assigned to Abu Ghraib, he believed, like most of his fellow soldiers, that the prisoners were among the most dangerous individuals in Iraq.

He said: "Most of the guys thought, 'Well, they're out to kill us. These are the ones killing our buddies."'

But while at work in a headquarters office, he said, he learned that most of the detainees at Abu Ghraib had committed only very minor nonviolent offenses, or no offenses at all. (Several investigations would subsequently reveal that vast numbers of completely innocent Iraqis were seized and detained by coalition forces.)

Several months ago Mr. Delgado gave a talk and presented a slide show at his school, New College of Florida in Sarasota. To his amazement, 400 people showed up. He has given a number of talks since then in various parts of the country.

His goal, he said, is to convince his listeners that the abuse of innocent Iraqis by the American military is not limited to "a few bad apples," as the military would like the public to believe. "At what point," he asked, "does a series of 'isolated incidents' become a pattern of intolerable behavior?"