The prisoners even nicknamed the most macho and brutal guard in our study "John Wayne." Later, we learned that the most notorious guard in a Nazi prison near Buchenwald was named "Tom Mix" -- the John Wayne of an earlier generation -- because of his "Wild West" cowboy macho image in abusing camp inmates.

Where had our "John Wayne" learned to become such a guard? How could he and others move so readily into that role? How could intelligent, mentally healthy, "ordinary" men become perpetrators of evil so quickly? These were questions we were forced to ask.