Sorry Joe, but

1. There is no statute of limitations on murder, nor should there be.

2. RE: once the criminals are dead, I think it's time to leave well enough alone: You feel they should be given a pass because they're old? Age is a defense against murder? I don't think so.

3. RE: prosecution of Nazis who perpetrated war crimes (Or Nuns who committed murder) "does no good", I would call your attention to George Santayana and that his famous aphorism "Those who cannot remember the past are condemned to repeat it" is inscribed on a plaque at the Auschwitz concentration camp.