So while everyone else is talking about RCT and his supposed Taguel power (Don't mess with the bunny!), I think there's an elephant in the room that needs addressing: ConeGamer. Or rather ConeGamer being here on Day 2.
Whether it was a brilliant mind game, an idiotic move, or a bold faced lie, Cone has outed himself as a Cleric character. Whether this is concete evidence of his ability, we do not know. However, if he is not scum then I would presume scum would consider him a top target for a night kill. I get that Prof is a classic night one choice, but when scum has an educated guess on who the doctor is, I would presume you would take it.
So here's what I've got:
1. Scum didn't believe Cone's claim.
2. Cone is scum.
3. Scum assumed that Cone would be watched/protected.
4. Bus Driver
5. As guessed already, the second killer is a SK/Vigilante (but the question remains: Why choose Prof over Cone?)
If both RTC and Cone are telling the truth, then it would only point to one Mafia faction and a SK/Vigilante.