Footnote 3: In Brachos 19a it says that if a Tzadik does a sin we assume he immediately did teshuva unless in a case of where he did not return the item he owes the person he took it from. This would seem to preclude that even if a person seems to have changed his ways for the good he is not considered a baal teshuva if he has not returned what he owes. If why does it seem that we are saying here that once we see a person has changed for the good then you can never speak slanderously against him because we can assume he repented, if he didn’t return what he owes he didn’t repent?
The answer is that the Gemara in Brachos and also in Bava Metzi’a 62a which also says, if he relented why does he still have the money, is talking about case where he is able to pay back and he doesn’t then we can technically speak out negatively against him as long as we meet all the prerequisite which will be taught in chapter 10. But here we are talking about a person who didn’t out right steal but rather he was a sleezy, dishonest businessman wheeling and dealing, forcing people to buy or sell things against their will. He became disliked and known by all to be very tough guy to deal with. One day he realized his mistake and changed for the good, becoming an honest businessman man known to all. In this case and in similar cases where it is virtually impossible to return everything he dishonestly took from so many people or he doesn’t have the means to return everything then once he has proven to have completely changed and is now an honest fellow one cannot bring up what he used to do and slander him.
Footnote 4: If one saw someone do a sin he must go over to the guy in private and politely, and gently rebuke him. Only after he repeated his sin in a manner that shows he doesn’t care about the rebuke and about mending his ways than one can publicly embarrass him into repenting.