If I understand it, according to Halacha, if Reuven steals $100 from Shimon, he has to first return the money (possibly plus another $100), apologize; then regret, confess, resolve, and abstain. If he's done all of that, he's done repentance (teshuva); and if I'm not mistaken, he would now be considered a kosher witness and no longer a "thief."
Where does government punishment fit into all of this? Suppose Reuven committed tax evasion/fraud, and served time in jail (and has also regretted, confessed, resolved, and abstained); is that good enough teshuva? (I don't know what monetary fines the govt. imposes, or what happens if Reuven since lost the money?) What if Reuven stole from his investors? From a corporation?