Chance of dying should always be lower than chance of escape in my opinion. For example, heroes have a chance to die in battle, but how often do you see a hero actually die. I think having a chance, even a small chance to die will make everyone think twice for characters they want to keep around.
I think it would be fun if after a few days, they get bored of you and just beat you up and toss you in a ditch somewhere to die leaving the character free of prison but wounded or seriously wounded.
