Crime is not sin. It is a mistake to equate them I think.
Do you think of all crimes as not deserving punishment, or just capital crimes?
Crime is sin in the eyes of God, unless it is a crime defined by man which opposes the law of God.
You have to ask, What's the point of punishment? Is it for the sake of justice or morality? Then I say that's been taken care of 2000 years ago.
So what do you do with a criminal? IMO, the first job of civil law is to protect society from dangerous criminals. So incarceration for criminals dangerous to society is mandatory with a reformed penal code and prison system that makes the prisoner productive and pay his way and don't let dangerous criminals out.