Can a Mass Murderer Redeemed?

Is redemption possible for someone who commits truly heinous crimes? Someone like a Nazi, a child molester, or a perpetrator of genocide? More specifically, can a fictional character who commits such crimes be redeemed?

A recent controversy in the literary world brought these questions into sharp focus. And as so often happens, the answer depends a lot on definitions. (As a self-confessed word-nerd, I am not a bit surprised). So, if somebody asked me the above question, I would have to respo...