Scenario one:

Day one: Lynch; possible hit on the mafia. 25% chance (4 choices besides yourself)
Night one: murder; leaves us with 3 remaining.
Day two: Second chance to catch the mafioso: 50/50 choice (you won't vote for yourself)

Scenario two:

Day one: No lynch. No mafia dead. 5 remaining. (0% chance of killing mafia)
Night one: murder. 4 remaining.
Day two: no lynch. No mafia dead. 4 remaining. (0% chance of killing mafia)
Night two: murder. 3 remaining.
Day three. Only chance to catch the mafioso: 50/50 choice.

I like the odds better in scenario one.