We've definitely had traitors before. I think in some games the mafia was made aware of the fact that there was a traitor out there and they could recruit him instead of killing whenever they pleased. Sometimes they just had the option of choosing any player they wanted and recruiting them. One game the traitor was promoted to Mafia Cop when recruited.

Whatever the case he was mafia aligned. If we look to his supposed investigation targets we may find some scum. He may have listed his buddies in an effort to distance himself from them.