First, after any player is lynched we analyze his posts with the new knowledge of the role reveal. If he is scum, look for suspicious interactions with the other players. If he is town, you can trust that his logic was meant to out scum, rather than distract.
Second, we examine the voting players. Were any votes placed with little reason? Who didn't vote on that player? why? ...and so on.
The "can a mafia kill mafia" question leads me to beleive you have no clue what is going on. Would you please read some of the other threads, maybe a FAQ, than get back to us?
If you are so suspicious of Remus, why did you vote for
-Peter