RED JOHN IS NOT KIRKLAND- why would he steal information from Patrick's room if he knew the list already?
RED JOHN IS ALSO NOT BRET PARTRIDGE- Bruno Heller isn't going to copy Dexter Morgan by having the forensics guy be the main killer.

Red John is Gale Bertram and here is my theory

Red John is known to wear a baseball cap probably to cover up the balding on his head in which Gale doesn't have much hair left. I also think the whole Rosaland thing was the fake clues in which Bruno Heller was giving because there is  no way a blind person can come up with height size etc and Bertram could have been wearing wig also.
(When Gale first comes into the CBI in Season 3x1 Jane gets a weird vibe from him.)
The first thing Gale says right when he meets Jane is (so this is the Psychic Boy Wonder meaning he knew Jane was famous in his youth. Also his first episode in which Bertram appeared was directed by Bruno Heller himself.
In the episode where Hightower is framed as the killer of Todd Johnson, Bertram, in a strange scene with Lisbon and Laroche, quotes a poem by William Blake. (LaRoche was the one who identified it as Blake.) Red John quoted a different poem, "Tyger Tyger" by William Blake, to Jane when he rescued him from being killed by deranged college kids who were killing people Red John- style.  On his deathbed in a hospital burn unit, Todd Johnson's last words were the title of that poem.
Then when the whole hightower thing was going down Jane asks Gale Bertram where he was and why isn't he on LaRoches list he doesnt reply.
Then shortly after that Jane and his crew setup a sting operation to get Red John which involved sitting down with Gale Bertram sitting at the mall with Patrick and hinting (your at the end of your rope) which then tells Jane that the mole in the CBI was Craig O. Then out of nowhere Gale gets up and storms out of there like he knew something was going to go down. Then the next day Gale was reading the EXACT SAME NEWSPAPER THAT CARTER WAS READING and why the would Gale be reading a newspaper that Carter was reading the previous day after all this went down. Then Gale told the lawyer to make it possible that Jane has no bail from jail so he could cover up his tracks while Jane was in jail. Why else wouldn't Bertram defend Jane for supposably killing the person that murdered his wife and child.
Jane also says:"(Red John) thinks I'm the fish and he's the fisherman" ("The Crimson Hat"); not only Minelli, also Bertram is probably an expert fisherman; from 5x01 in this office he seems has an award of fisher competition, a statue of a fisherman, behind this desk.
The note on the wall from the motel where hooker wrote on the wall was "HE IS MAR" could mean he is married which Bertram is married. Then to skip to season 5 where Bertram and Kirkland had a private conversation about trusting Lisbon on what facts Jane knows about Red John is pretty sketchy to me. I think Kirkland is Red Johns right hand man that broke into Patrick's Room just to make sure he did the list of the 7 suspects correct in which they were (confirmed by Heller himself in a interview he had on season 6). Bertram has all the resources possible to be Red John and access to everything Jane does to ALWAYS be one step ahead of him. 

This is just my theory out of everyone on this list i think that Gale Bertram is Red John.

Since we have to wait till the Fall to see another episode, I figured I'd try to get some theories going on a different question:

HOW will Red John die? (if at all)

Here are some possible theories I came up with:

-Jane kills him like he said he would all along
-RJ kills himself before (or during) his capture
-Lisbon or Kirkland (or another agent) shoots Red John because RJ is about to kill Jane
-One of RJ's followers kills him when he gets captured, just like all of his accomplices were killed, before Jane has a chance to kill him or bring him in

Any other theories?  Or additions to my theories?

**Also, side not--  I put Kirkland in one of those theories because I still believe he is a good guy trying to find Red John.  I posted a theory that he was a good guy after the episode that he shook hands with Jane and people started thinking he was bad.

Gale Bertram can be Red John.

First of all, Rosalind was in a defensive state when CBI accused Roy for being Red John, so her description of Roy might be a lie. Or, Rosalind was told to describe Roy that way by Roy, we don't know.

We also see that from the list. Gale Bertram is on the list despite he is bald. This means Patrick doesn't take the description of Roy by Rosalind into consideration.

The only thing he takes into consideration is that he has shaken hands with RJ. This is true because Lorelei said that when she was super angry.

Now, let's have a closer look at season 3 finale. I am a fan of Timothy Carter character and my favourite episode so far in mentalist is season 3 finale.

To understand season 3 finale better, we first visit season 4 episode 1.

1) Ron Deutsch, the security guy who removed the gun and cell phone from Timothy Carter's body, is found dead. 

He was asked to remove them. And in the end, he was killed to make sure he tells nothing.

The question here is: Was he planted there before the meeting to remove the stuff, or was he a regular guy working there and when it was understood that meeting was to be held at mall, a guy of RJ told him to remove the stuff in exchange of huge money.

I think he was a regular guy and maybe they offered him a million dollars. This way he accepted it.

Now let's finally go to season 3 finale.

2) It is only a moment between Timothy Carter's death and security guy's removing gun and cell phone. This can only mean one thing. The deal was made before Timothy Carter died, possibly when Jane and Bertram arrived at mall, or within few minutes after that. Security guy was planted before meeting or deal made after meeting, doesn't matter. 

This only means one thing. RJ knew that Timothy would die. 

How does he know that? If Jane had never met Timothy, Timothy would just drink his coffee, read the newspaper and leave the mall.

So we look at the reason why Jane and Timothy met.

3) Jane spotted Timothy because he made the phone call with Lisbon. 

Why? Because Craig O'Laughlin was dead and Lisbon used his phone to call last dialed number.

So, if Craig O'Laughlin was not dead and killed Hightower, Lisbon, Van Pelt, Jane would never spot Timothy and he would not die. This means that O'Laughlin had to die that day.

4) Craig O'Laughlin died because Jane realised that the real mole was O'Laughlin, not Bertram.

Bertram: You just sound like a man who has pushed himself too hard, who has reached the end of his rope.

This was the reason why Jane understood that the mole was O'Laughlin. Without this sentence, Timothy would walk again.

Now, Timothy was there to die, but I doubt he was aware of it. But the plan of RJ was that Timothy would go to mall, talk to Patrick Jane, and Jane would kill him. And only one thing would make this come true, that Jane realizes that the mole is not Bertram but O'Laughlin. And without this sentence, it would never be possible.

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I have always thought that there were 2 moles in CBI. Now let me show you why. I had written theories about it before, but could not find link, so this is a re-write.

The assassin takes fire stairs, goes to Bertram's room, puts rope and stuff on the bed and just waits. And when Cho and Rigsby arrives, she is not surprised at all. She just smiles and jumps to death. How do you do that, if you weren't expecting it.

This means that RJ knew it was a trap. Why? Because both O'Laughlin and Bertram were moles ( Or Bertram is RJ). Two different hotel numbers coming to RJ, meaning it was a trap.

So RJ sent an asssassin with rope, and Bertram used a sentence with "reaching end of rope". And this way everything happened according to RJ's plan.

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Now I want to tell another reason why Timothy was there to talk to Jane and die. It was a historical meeting, and hence planned before. It was very important for RJ, so the content of the chat must be important too. RJ can't just tell him to go there and improvise. Whatever Timothy says, it must be RJ's words. So either:

A) RJ and Timothy practiced it before. RJ told Timothy what he should say and also how Patrick's wife and child smelled.

B) RJ was there, listening, telling Timothy what to say through a bug in his ear. This can also explain why Timothy answers Patrick's questions with 2 second delay and stopping here and there. If this is the case, Bertram could be directing Timothy his speech.

I find first option more likely. Either case, this was a very planned meeting by RJ.

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With Bertram's key role in this episode, even with one sentence, I think he is more likely to be RJ than anyone.

Maybe too obvious to be him (especially due to the William Blake poetry thingy), but I think out of the 7, he is most likely.
I think that Sophie Miller (Jane's doctor from psychiatric ward) is probably involved with RJ regarding Jane's old memory.
I can't see Partridge having the connections and power that RJ would have to have.
If RJ is Kirkland, why would he break into Jane's room for info when he had already rounded down the 7 suspects (as proved by Lorelei being alive (and don't give me any of that multiple recordings/cutting crap) before Jane got there himself. Also Kirkland seems waay to obvious, my theory is that maybe he has personal experience with RJ, wants his own revenge for something and wants to beat Jane or anyone else to it.
Stiles clearly has the ability to manipulate people in the way that RJ seems to, but in my eyes he doesn't have the right kind of personality. He is one of the most likely people I think, but again it may be too obvious, as his connection with RJ has not been hidden.
Haffner could be involved with Bertram and/or Stiles with regards to RJ, as Bertram assigned him to RJ case perhaps to find out exactly how much they knew. Or there could be some kind of visualize connection between Haffner and Stiles, if Stiles is RJ, Haffner may have been keeping him in the loop as Haffner is shown to be open to manipulation with visualize as proof.
I don't really have anything to say about Sheriff McAllister or Reede Smith, other than I would be disappointed if either of them turn out to be RJ, as I think it would be quite boring and I doubt the show's creators would choose anything so dull.
These have just been my ideas, and they show that I don't really have much of an idea of RJ's identity, but please comment if you have anything to question/add

I think it might be him. How can so many Red John supporters have work in his office? It is not easy to get recruited and be exactly in the office you want to be - he must have a say in recruitment/staffing decisions.

It took me a while to write this whole theory so please read before upvoting/downvoting.

We know, from an episode in season 4, when Roy pays Rosalind a visit and kills the morgue attendant to prove he's alive, that he wears a ring in his left hand: http://i.imgur.com/UZGYhAl.jpg (that pic is a little blurry, but if you see the episode in HD, you'll definitely see it).

Brett Partridge, the most likely suspect, doesn't. Here's him in episode S05E15, Red Lacquer and Nail Polish: http://i.imgur.com/erDT36y.png 

As for Kirkland, he doesn't wear a ring either, and he holds his drink with his right hand: http://i.imgur.com/Emn4cbH.png

Haffner - no ring: http://i.imgur.com/YLC8HCc.jpg

Same for Stiles: http://i.imgur.com/e7uvgso.png

And finally, Sheriff McAllister, no ring either: http://i.imgur.com/b8KhrTg.jpg

As for Smith, I couldn't find a video where he shows his left hand, but come on, the guy doesn't fit the RJ profile at all. Red John has a rather slim figure (not soft but not beefcake, as described by Rosalind Harker) and, according to the writers, his real face has been visible in episodes before season 4 premiered. This guy first appeared on S05E01 and I'm not sure if he even had any lines. I think it's safe to rule him out.

Bertram, on the other hand (well, not literally) DOES wear a ring: http://i.imgur.com/ifJRtcr.png

If the list can be trusted (and Heller isn't screwing with us), then, judging Roy Tagliaferro's appearance, Bertram is Red John. There's also him calling Patrick "boy wonder" in S03E01, his William Blake quote, the mall scene in Strawberries in Cream (how else did the fake Red John know he had to be at that particular mall at that exact time?), his resemblance to the mysterious police car driver in S04E24, etc.

There's however, other things that don't match. He's over 6 feet tall and he's mostly bald (according to Harker, Roy has short hair). The rest fits, though.

http://i.imgur.com/Ff60PVz.png

Despite the awful quality of the image, it looks like Gale Bertram