Yeah I killed them both, was a 2-shot vigilante. Looks like I suck at reading Onyx but I thought there was a chance I'd be killed so I wanted to go brave. Telling you guys this because this means mafia is waiting to stockpile kills.
Mafia cannot stockpile KP.
So either you're telling the truth and the Mafia is either made up of inactives/dumb/has something up their sleeve (though I have no idea how not using their KP would benefit them), or you're lying. Hmm...