The face of evil?

Even Nietzsche might have called Duch (born, Kang Khek Ieu) evil. He was the Khmer Rouge's chief interrogator, torturer and executioner of the Cambodian intelligentsia (from 1975-1979), and in a recent interview he reminisced:

I and everyone else who worked in that place knew that anyone who entered had to be psychologically demolished, eliminated by steady work, given no way out. No answer could avoid death. Nobody who came to us had any chance of saving himself.

Click here to read snippets from that interview with the "Cambodian Himmler."

After many years of negotiations, he and other senior Khmer Rouge leaders soon will be tried.

I've exerted a good deal of intellectual energy reading and reflecting on evil, but there is simply nothing that comes close to accounting for its existence and expression. In the interview, Duch appears to suggest that fear (for himself and particularly his family, who he claims was held hostage) motivated him to do what he did. Duch has since found Christianity, and this retrospective rationalization is an evident attempt to disassociate his present self from his past incarnation. This is all well and good, but does nothing to explain his mindset in Democratic Kampuchea circa 1975.

Unlike Eichmann's, Duch's activities and the innovation and zeal with which he approached his duties, cannot be characterized as banal.

How should they be characterized?