Prisoners strongly encouraged to donate or sell their organs, bone morrow, body parts while alive and at death. Donate enough and you get your prison sentence reduced or get better treatment. Too many law abiding people need organs and until science perfects artificial organs then this is good source.
Gladitorial Games where murderers and rapists and lifers can fight each other to the death. A good fighter that shows remorse should get their freedom. It will reduce the prison population. It kept the romans happy for many years it should be good enough for Americans.