From the looks of things, I think Ingus isn't Mafia. Well, he sounds like he'd be of use to the town if kept alive, and I guess what he did had good enough reasoning behind it. Unless he's a smart Mafia person.
But, since I don't think he's Mafia, the people I'll be thinking about those that immediately voted him - although, Fran probably felt threatened; I'd probably have done the same if I were in that position. So, maybe a little suspicion falls on Ramza? And then Edgar, who is just bandwagoning for no real reason. Suspicious indeed.