I definitley think Red John is Ray Hafner.

Red John was under 30 in 1988 and worked at the farm... Hafner was 21 in 1988 and he acted like he worked at the farm

Visualize and Red John are somehow connected... Hafner is a member of visualize

Maybe when he offered Lisbon that Job he was trying to get her on the Red John Team

Think about it.

It is Ray Haffner... At least that's what I read from the latest episode...

Did anyone else just watch the new mentalist lisbon wanted to know thoses names really bad maybe it is her 

I believe that red john is a genius that enjoys puzzles, because he has created a very intricated network of disciples which he really doesn't need (you might argue that his people in the FBI and CBI have helped him on several occasions, but apart from the killing of vasco's team, he would never have gotten in such situations if he didn't have disciples in the first place, and rebecca's "hiring" was a rather "momentary" thing) and it can therefore be argued that he has only created that network for the hell of it, so to speak. Because of that, I think Red John is the man at the puzzle store, in the episode of the universal hack and the dead mathematical genius, and that he respects Jane enough not to kill him beause jane beat him at chess.  

It cant be Jane because why would he kill his own family.
I think it could be Teresa Lisbon but it might not because she is the leader and she always seems upset when she sees someone die but she might be because when she has a bad guy shes not afraid to kill them even if there is no harm in her or anyone else's way. So that is why I think that it could be someone else because all of the people on there could keep the secret of killing Jane's family and still work so close with him and be such great friends with him.
So it must be someone else

Right now my top suspect is Ellis Mars aka Lamar Ellis

In Season 2 Episode 2 (I think), Jane has a conversation with Bosco in which they play on the phrase "Cover Up" and as Jane is leaving Bosco drops the file in a basket covering up another file that read:
Superior Court - LA County
   Statements - Case# 42-53-2A
Attn: Lamar Ellis

Then in a later episode we meet a man calling himself Ellis Mars pretending to be a psychic.  He acts a bit goofy to throw everyone off but he correctly predicts there will be another murder.  Then when Jane has Mars in the hotel room and the killer, a Red John accomplice, comes in the Killer says to Jane "It would blow your mind" in reference to who Red John is.  That Jane had Red John (Ellis Mars) right there in the room would blow his mind. 

My #2 suspect is Bertram and his assistant.  This works for many reasons already stated in others theories.

In Reality I doubt that Bruno Heller has decided exactly who will be Red John.  He has left things open enough that it could plausibly be 10-20 different characters.  Also with Red John using so many accomplices any one who appears a solid suspect could be written as just another accomplice.

Okay, after all i've red some of these ridicilous theories i will make the most accurate theory ever; and it's 100% true shot. Here i say it this might be a big spoiler from cast so if you dont wanna ruin the show better u dont look at it but i must say Red john is Red john.true story