Since Thar was revealed to be a Jester, I'm not convinced that Mezlo is a Jester. I do think Mezlo is anti-Town though, given his behaviour on Day 1 and odd300's lynch.
However, I haven't thrown out the possibility of duplicate roles. Since Sarah was "the Sane Cop" rather than "the Cop," there may be another Cop. Furthermore, the night scene may suggest that there are 2 Doctors, assuming no one switched roles; if the 2 figures who bumped into one another switched tools, but not roles, then they must have the same role (role and tool type correspond). Similarly, there may be 2 Jesters.
I'll keep my vote on Mezlo, as I think lynching him will at the very least provide us with some clues.