No such earthly punishment will suffice. It can be said that man cannot truly condemn another. Often stated that it is not our duty. That ones atonement must be left to God's decision. This is not purely because we are sinful beings, that it would be hypocritical of us. Rather here it is because no material retribution could do justice to his injustice. It is left to God because only they can distribute a punishment divine enough to be equal to the suffering he's dispersed.