I believe Bret Stiles is Red John. (If this is the wrong person i am talking about and his name is different, excuse me for that :P)

Firstly, Bret knew where Kristina Frye was kept after she got stolen under security of the Team.
He gave exact directions to the house she was in (Why did he do that? I do not know) and when Patrick Jane got there she was in a room with no furniture and only a chair and she was sitting in it. Her face blank. she only gave contact to Patrick Jane when he "summoned" her from the dead and talked to her in a dark room with a candle. But easily that could be hypnotism and Bret can easily do that. He could have hypnotised her and made her believe she is dead and can only talk to the people who summon her from the dead and forget who killed her.

Lastly, Bret has a lot of power which he can use. In Season 5 Episode 8, In the beginning, Jane goes in the movie theatre and watches an old movie with him. They used that as a secret meeting place. And Jane asked Bret to get Loralie out of jail for him and he neglectively agrees. ( Neglect a sign of "i don't wanna do this !"?) He does it easily. And Loralie was in a very high security prison. Bret's nickname could be Roy. (Im not sure about this next part) Bret might dislike Jane very much but not show it... also a sign of (Season 5 Episode 8) I can't believe you weren't good friends the moment you shook hands with Red John. (Loralie says that.) 

P.S Bret Stiles (not sure his real name) plays the bad guy ALWAYS in movies. 

P.P.S for the "I disagree" people who read this:
He might not be Red John. He looks very kind and doesn't look very serial killer-ish but then again he could get other people to do his dirty work for him, He might not be Red John but there IS some sort of connection between Him and Red John.