Justice is a great ideal, I like to uphold it as much as reasonably possible, but it's intangible and nothing but a fabrication of humanities need to see things that upset them atoned for without infringing on it's own ideals too often. In this case the man would be very old, he now is no threat to anyone and I am told he is utterly repentant, however he wants to avoid jail. I can see a few reasons for this, he may have grandchildren he doesn't wish to be separated from or he may simply fear what awaits an ex-nazi officer, but either way it doesn't change that sending him to prison at this point won't constitute justice; it'll be a hollow gesture to a situation where the fantasy rules of justice can't find a solution that makes sense, because there isn't one. Life, the universe, it only makes sense in the most logical of fashions, there is no balance of deeds and misdeeds, and in this case there is no longer any need to attempt. If there is an afterlife he will reap what he has sown or see mercy / reward for his penance and altruistic nature, and for those who believe there is not they must make peace with the uncaring entropy of the universe and of life. This man would not benefit humanity by going to jail, he has changed, and his crimes are his own personal demons. If he didn't care about what he'd done, he wouldn't begin now and we can't force him to. Killing him would be a futile and helpless gesture further compounding the inability for justice to sit comfortably here.
Who is he today matters more than whom he once was. To whether I'd harbour him however, no probably not, but I'd stand for him in court and testify to his kind and repentant nature, and impress the lack of necessity in imprisoning him. I'd understand if they did. Maybe he should have been in jail all along, maybe he should have never had grandchildren or spent his later years free of the fear of persecution and hostility. I cannot say.
Some might say he deserves to live his final years in anxiety and loneliness because he did the same at some point to many others. I don't believe killing a person makes up for him killing many other people, and the same is true here, to me. It'd be empty suffering from a time when so such cruelty was already done.
I would not contest sending him to jail though if that was the verdict as, as I have said, I cannot say what is right. There is no justice here.