What if someone was a violent criminal in the past, like due to an Alcohol addiction, but went through therapy in prison and is now a peaceful citizen? Serving

What if someone was a violent criminal in the past, like due to an Alcohol addiction, but went through therapy in prison and is now a peaceful citizen? Serving your time in jail is sufficient to pay for your crimes, IMO. Unless there is a good reason, ie public interest as the law states, we shouldn't rubberstamp all criminals as evil (or all violent criminals). Part of getting them back into society is rehabilitation which means we give them another chance to integrate and follow the law.