This situation is not unique and there has been some research on it.
New York Times May 6, 2004
Simulated Prison in '71 Showed a Fine Line Between `Normal' and `Monster'
By JOHN SCHWARTZ
Published: May 6, 2004
In 1971 researchers at Stanford University created a simulated prison in the basement of the campus psychology building. They randomly assigned 24 students to be either prison guards or prisoners for two weeks.
Within days the "guards" had become swaggering and sadistic, to the point of placing bags over the prisoners' heads, forcing them to strip naked and encouraging them to perform sexual acts.
The landmark Stanford experiment and studies like it give insight into how ordinary people can, under the right circumstances, do horrible things ?- including the mistreatment of prisoners at the Abu Ghraib prison in Iraq.
What is the distance between "normal" and "monster"? Can anyone become a torturer?
Dr. Philip G. Zimbardo, a leader of the Stanford prison study, said that while the rest of the world was shocked by the images from Iraq, "I was not surprised that it happened."
"I have exact, parallel pictures of prisoners with bags over their heads," from the 1971 study, he said.
Link to NYT