So here are the possible reasons for THREE nightkills on night zero.
1. Mafia (obv)
2. SK (likely)
3. Rival Mafia (I hope not, but this seems very in flavor =/)
4. Noob Vig (If this is the case, and you vigged the doctor, then, damn, bet you're not going to fire night zero ever again, lol)
Almost forgot (No, I'm lying, I actually didn't)
If you "have something" on me, lets hear it, mate.