In short:
Cop
1.
Maf? (yes)
2.
Town? (yes)
3.
Has a killing night ability? (yes)
1 lie, 2 and 3 are true. Cop is a priest/knight/warlord
2 lies, 1 and 3 are true. Cop is a mafia member.
3 lies, 2 and 1 are true. Logical collapse, this option is impossible.
Conclusion: Cop has approximately equal chances of being a town member and a mafia member.
Added after 12 minutes
I don't understand, is Revan being punished for being in the block when the mafia didn't kill?
That's harsh!!!