In the preview we hear a voice supposely from the guy in the church. He seems to be above mid-age and grey-haired. I'm quite positive this is Judge Manchester, he has the same rasping voice. Also seems to be alternating between quite low and high pitch.

Preview:
http://www.youtube.com/watch?v=wrzRijdiKcM

Judge Manchester:
http://www.youtube.com/watch?v=iUWHRbPKPME#t=31

My guess is that he's the leader of Thyger Thyger, the question is if he's also Red John or not. It would feel like a bit of cheating to have such a character being Red John. There's no evidence so far that he's the mastermind killer.