They absolutely have not “paid their debt to society” unless they can undo the felony. You can’t pay back the debt of raping someone or stabbing them or killing them. Even if they let you out of jail.
Then why do we let them out of prison at all? It's certainly safer for us law abiding citizens if all the criminals are locked up forever. Even if there are a few false positives.
By that logic, anyone who is proven then to be involved willingly or not in the false accusation and wrongful imprisonment of anyone should be punished by the harshest means physically possible. Absolutely no mercy.
Willfully? Absolutely. I think willfully trying to get someone convicted of a crime should carry 3x the punishment of that crime. It’s the deliberate misuse of state power to pervert the course of justice.