No one has counter claimed Sheriff. but its possible that there wouldn't be a sheriff in a game with the CDC who investigates.
AV was right about Jazz, but he could be a mafia investigator. His play on MR could be trying to protect a team mate or PZ could be immune to being found by the real sheriff. In such a case Ceres must have bussed his easiest to hide team mate.
Working backwards, given that I believe Falcon is the doc, he really did protect AV who was targetted and correct about Jazz, and PZ is prob investigation immune.
I don't think Ceres would bus a valuable (potentially allegiance converting) teammate. Though I don't like how Ceres is talking out his ass about his powers and actions, it keeps us and the mafia on our toes