I didn't pay much attention to this mafia, mostly just checked to see who died. Looking back, were any of the mafias obviously mafia? On another note, the longer some players live, they more likely they are to be mafia (mafia likes tends to kill people they see as more threatening). I have the impression that Rob is one of these players. Am I correct? If so, why didn't you lynch him 2-3 rounds prior to now?
That's just one strategy I follow as I familiarize myself with the people I play with. People still alive once mafia starts killing people I don't see as priority nightkills are much more likely to be mafia.