Interstellar Travel - Criminals

Eventually, it will happen. The first murder in Interstellar Space. And when the culprit is caught, what will be done? Out the air lock? Doubtful. All materials must be preserved in the system - eliminating that much mass would throw the balance out of whack. So death? What about for lesser crimes? Will there be jailing facilities? Judges? What system of justice will prevail?

And, will the focus be on rehabilitation or on punishment? It would seem that all but the most serious of crimes would be given sentences that allowed the offender to still participate in the running of the ship. Noone can be idle by, and especially in a close environment like that, it seems at first glance that an idle prisoner would stir resentment, and eventually if the crew was too hard worked they would just opt to break a minor law and serve time doing nothing.

A judge must be present, which means that there must be a law branch of the school. And enforcement of laws requires police. Naturally there will be security, but to what levels? And would the military be involved at all in day to day penal matters, or would they even be involved in high crimes such as insurrection or assassination?