The Last Nazis

There is a show on Netflix I started called "The Last Nazis". A Nazi Hunter spends his life finding those who escaped conviction after WW2. There are supposedly a select bunch that have done evil things and are still living under the radar. For example, Dr. Death. A Nazi doctor who did evil practices on the concentration camp victims. Or the lead soldiers who guided the victims into the chambers to kill them. There are various different positions of the people he seeks out. All very obviously evil people though. My question is...these men are roughly 95-100 yrs old. Should they be left alone at this point? Are the crimes so old (70+ years even) that there is no way to make a real conviction? Could they have really changed over the course of so many years and have a change of heart, causing them to be imprisoned with their own guilt? Or do they still deserve prosecution and prison?

Note: Yes, some of them are confirmed to be still alive.