In my humble opinion, once they are found guilty in a court of law then they should forefit their lives and make a chice:
A) If they want to have a painless death then, they should agree to their orans harvested, a least that may atone in some sma way for their disgusting life choices!
B) If they refuse to donate their organs then skin them and bury them alive in a salt pit to bleed out!
Now I agree that may sound a little over the top, but that's just my humble opinion...