Prosecutors believe, for instance, that the only thing wrong with the Crucifixion was that the state didn't do it again when the opportunity arose. Therefore, the official line will be that the guy was rightly convicted despite this recantation and he'll stay in jail.
It's all dependent on his involvement in the crime. Perhaps he was an accessory after the fact. Somehow, I assume he was involved in the murder, even if he didn't actually commit it.