When a country is conquered, what happens to its criminals?

Take, for instance, the perennial favorite example of message boards, Nazi Germany. In Nazi Germany, it was illegal to be a Jew, homosexual, Communist, or Jehovah’s Witness, and these people were put in concentration camps. So the allies win, they come in, and they set the prisoners free, right? But wait. Surely even in Nazi Germany, such things as rape, robbery and murder were illegal (at least when done without the sanction of the Nazi Party). So presumably the concentration camps contained prisoners who were there for not-so-innocent reasons. Just because someone opposes an evil regime doesn’t mean they’re good. So how is this handled? Do the conquerers say “Well, anyone conviction under Nazi rule is invalid, so you’re all free to go?” Do they have hearings to evaluate the legitimacy of the charges?

What about charges stemming from events during the war? Is killing a cop after the war a capital crime, but killing one during the war an act of resistance? Does “it was justified by the war” become a defense? If so, is it an affirmative one? If the wartime governent provided exemptions from prosecution for certain crimes (eg murder is illegal, unless it’s of a Jew), or didn’t recognize some things as crimes, will the new government retroactively declare these to be illegal?

The case of Germany is the first that jumps to mind, but I’m curious as to how occupiers in general have handled these questions.

they’re set free, only if the place surrounding the prison is plundered (or raped) regardless of what they did. They may be put back into jail later

Most “ordinary” German prisoners were not in concentration camps, but in “ordinary” prisons. I think that some convicted of serious crimes would have been sent to camps, but I am not sure about this, or about how the matter was dealt with under the allied occupation.

Presumably the camp records would have showed which inmates had actually be tried and convicted, and of what, and which were there simply because of an administrative decision to detain them. So it would at least have been possible to attempt to treat the two groups differently.

It is worth pointing out that the usual pattern was not that, the day allied troops arrived, the camp gates were opened and the inmates streamed out. The generally stayed there for some time, because

(a) they had nowhere to go

(b) they had no clothes, ration cards or other necessities of life, and

© the allies didn’t necessarily want them roaming the countryside.

Did they stay because they had no practical choice, or because they were actually required to stay? I don’t know. Could they leave if they could establish that they did have somewhere to go, and people who would look after them? I don’t know that either.