After reading through most of the thread again (almost 60 pages is way too much to read in one sitting) I've compiled a list of my prime suspects:

Plum Kitaki: Mostly because of bandwagoning and inactivity.
Damon Gant: It's seems highly likely to me that he was behind Kristoph's murder. As has been mentioned, all Kristoph did in day one was vote Gant. Therefore it's probable that Gant wanted him out of the way to save his own skin. It may have been a rash move on his part, but it screams scum to me.
Jean Armstong: He's too smart for my liking. Granted he might be trying to unite the town, but mostly it seems he's trying to turn us against each other. He may be a sexy manbeast, but he's definitely got some kind of power role. Mafia or not I don't know yet.