1. Ruling out any possibility that PJ himself is RJ. Why? That's just odd writing on Heller's part if it turns out to be some Fight Club scenario. Plus, there are so many evidence pointing AGAINST that theory.) 

2.Ruling out any NEW suspects that are featured at the latest seasons both 4 and 5. ESPECIALLY KIRKLAND-freaky homeland security guy. Why? I know his voice matches and everything but HE IS A FAR TOO OBVIOUS CHOICE. His character is an intriguing one, and could probably be RJ's friend but RJ himself? I don't think so. In fact, any new suspicious characters introduced to the series from S4 onwards I believe are either on RJ side or PJ. THAT DOES NOT MEAN THEY are RJ HIMSELF specifically. 

I believe the writers' themselves already have slipped in that RJ character into the first 3 seasons of the series and in that way, when the final reveal occurs, it is revealing and make sense to the longterm viewers. Good writers often do that at least. 

3. Ruling out any one from the Team, except maybe Van Pelt might just fall into RJ side accidentally but even then, I doubt so. 

4. Ruling out females. Erm Rosalind, Kristina, Lorelai, Hightower etc.. I caught the writers saying RJ is a man in some random interviews so... and if not how can Lorelai be RJ mistress? Lesbian? No.BTW Kristina is an interesting character as well, I hope they bring her back in the sense that she in her state of mental instability contributes in some climatic scene haha such as helping RJ unintentionally. Also, I believe Lorelai might just flip and help PJ in the end. 

This leaves us with whoever we already know so far. RJ is a male, someone with connnections thus a person of authority and even more specifically shook hands with PJ before, someone PJ knows-from the older episodes.

Somehow, my strongest guess is Gale Bertram but LaRoche is a close second followed by Minelli . Gale Bertram fufils the criteria above and more importantly has been behaving the least suspiciously thus making him the prime suspect. I mean at the end of the O'Laughlin episode, he was at the scene of the crime. When someone supposedly took off with the fake RJ's gun. Coincidence? Hmm..also at the end of one of the recent episodes(the newscaster one) there was a zooming out effect when Kirkland was talking to Lisbon and PJ warning them against the rich evil guy? A picture of Bertram (i think?) was hanging behind in the background as the camera fades out and was kinda creepy in a Big Brother is watching you kind of way. I think it was intentional. 

I think is is Michael Gaston's character, Gale Bertram.

I think its highly unlikely to be Patrick for a few different reasons. One, there happens to be a couple episodes where Patrick and Red John are actually in together. For example, the one where Red John recites a poem in Patrick's ear. Or where Red John slips a note under Patrick's hotel door and he chases him down. I disagree with the theory of Red John actually being Patrick.

Well,just finished season  4......I always had a hunch about bertram being RED JOHN specially after the poem incident where he quotes lines from the same poem i.e. William Blake's as Red John does....
Now,if you happen to watch the season finale of season 4 closely,you can't help noticing that Jane,Lisbon,Van Pelt,Rigsby and Cho are out of the question.
The final scene shows a white police cruiser speeding fast alongside Jane and Lisbon with a big bulky man at the wheels,which in my opinion,is Bertram.Zoom in and check it out.

I'm only on season 3 episode 17.  And after reading some theories I do believe that there is some possibility to there being multiple people versus just one.  But what makes me think it is Bertram is at the end of episode 16, season 3 Bertram recites a poem to Lisbon.  Bertram recites a poem, smiles and then says "just a little poem I like" and walks away.  LaRoche says, " William Blake, I believe"  The verse that is recited to Jane, "Tiger, tiger.." is also William Blake.  Coincidence?  I think not ;)

I think Red John is one between:
1) Director Gale Bertram
2) Officer Ron (CBI Ron)
3) ADA Osvaldo "Oscar" Ardiles
4) Alex Jane, PJ's father
5) Officer Brett Partridge, CSI
6) Dr. Linus Wagner, psychiatrist, fake RJ
7) Walter Mashburn, billionaire
But I write the most possible theory, Bertram.

I find a proof against Bertram.
There are, maybe, very important. A link between Timothy Carter, the fake Red John ,and the Director.
First of all, I say that Carter could not have learned from O'Laughlin of the trap, would not have suffered tempoi, then has two RJ moles or he himself is the CBI, and has consulted with the mole and he understood everything. The killer at the motel only served to confuse and deceive Jane.
But, while Bertram is drinking tea when Lisbon is talking to him, reading a newspaper.
The next day at the mall, the same newspaper is in the hands of Carter (perhaps contains information on the family of Jane), after Bertram is go away.
Here are the photos:
http://i48.tinypic.com/4qob2u.jpg

http://i45.tinypic.com/msyc6c.jpg

I believe that Gale Bertram is Red John, furthermore, i believe that Red John is a puppet master, Merely a person who controls pieces on a chess board as a way to control things.

What we know.

Red John is connected, he has agents in the CBI, FBI, and the ability to put people where he needs them when he needs them.(numerous instances of rj knowing information he shouldnt, being able to upload to CBI's servers)

Red John was friends with the father of a sheriff hardy, which means Red John is older then he may be made out to seem, as hardy would be in his 30's at the time of the episode, hardys father was arrested 10 years prior, that would put Red John somewhere in his late 40's early 50's

Rosalind says that Red john is 
Red John has an average height short straight hair, 
He appears to be a Caucasian, and is a white person as described by Haley. This leads me to believe that the man Rosalind has been meeting with "Roy" is actually Bertams assistant 
(played by andrew leeds)  Drew Yost.

I believe that 
Drew Yost is the apprentice to Bertrams Master, I believe that the earlier kills were all commited by Bertram, and When Janes family was killed it was Yost taking over While bertram managed his stable of followers.

I believe that Timothy Carter, was indeed the man who came to rescue Jane from the student snuff film makers(listen to carters voice when lisbon calls to say Craig was dead)

I believe the person who killed boscos assistant to be another of RJ's followers.