If you take troops who aren't properly trained for guard duty, put them in a situation where the lives of them and their comrades are at risk 24/7 from an enemy that seems to come from nowhere, and then put them in charge of "enemy" prisoners with orders to break them down, of course things like this are going to happen. It's the darker side of human nature, and the darker side of military obedience. "But we were only following orders"