Come to think of it, I just had a brilliant idea.
Listen up gang:
Okay, let's pretend I'm mafia trying to save SirTommy.
Mister Bad Player, scan me tonight. We leave both you and Tommy alive. Then you'd have two results that say guilty instead of one, right?
And if we have doctor peoples in this game, they protect mister Bad Player so that he cannot die, and therefore he can return the scan on me tomorrow.
So, we'll have either confirmed that Bad Player is lying, OR, me and tommy are both mafia, OR, we will have confirmed that Celtic is actually guilty with the insane scan result (long shot but possible).
Agree to this plan and we will get to the bottom of all this. Disagree with this plan and you're all a bunch of freaking wimpazoids who can't think for yourselves and must rely upon investigators to save your butts and win the game for you.
Listen to Pizza. This is important.
edit- Oh and if I scan innocent and Tommy scans guilty and Bad Player flips town, I also just outed myself as the mafia godfather. That's sorta really counterproductive.