Thirty-two distinguished people wrote answers to Weisenthal, in response to his question. Here is the crucial question. Particularly if these people aren't sorry. If there is no repentance, no restitution. Forgiveness is an offense to our universal instinct for fair play.
Vengeance is one option.
If someone hurts you, the most natural thing in the world is to want to get even. Give back as much pain as they gave you. That would be fair. After the war, Engel was sentenced by the Nuremberg Court to thirty years in prison for atrocities committed by his army. He completed the sentence and was released.