A few previous theories on this regarding Gale Bertram have really got me thinking and now I'm almost 100% sure he's our man. If we look back to the season 3 premiere, he shows up at a crime scene simply to talk to the cameras, as he has a fierce interest in public image- just like Red John: he has killed atleast 4 people, simply for being made to look bad on TV. Who better fits that persona than Bertram? When he meets Jane, he shakes his hand and calls him "Boy Wonder", which can't just be a coincidence, I'm pretty sure it's a clue that he has a connection with Jane's childhood and the carni lifestyle(could explain the memory, and the Lorelai death setting). Probably RJ's idea of a joke. People would argue about his appearance, but I think it's clear now that Rosalind's description is inaccurate. Jane obviously doesn't trust it or else why would Stiles, Smith, McAllister etc be on the list? I think it'll turn out that she lied to cover for him, because she's still in love with him. In the season 3 finale, the main thing that bothers me is how Jane doesn't click, that the only way Red John could have arranged the plan in the mall, is if Bertram is RJ or atleast in league with him. Only they and the team knew about the meeting! If you watch the scene in the mall again, notice how GB keeps looking over at Timothy Carter. It's also interesting how they both read the same newspaper days apart, a subtle clue from BH? With Todd Johnson's murder, obviously O'Laughlin killed him, but what if Bertram was also there to make sure he got the job done properly, there was a lot at stake after all! He later knew he had to sacrifice O'Laughlin(convenient slip of the word 'rope'), to lead Jane to Carter and save his own neck, but probably didn't bank on Jane killing his friend. Hence why in season 4 he wanted Jane jailed and was clearly angered. Ron Deutzch, the bald security guard, was an insurance policy..there to recover Carter's weapon if anything did happen and to show Jane just how much smarter he was than him. But if you look closely, early on in season 3, Ron is visible in amongst a group of Visualise members.  In the following episode, Haffner is given Lisbon's job ( probably hired by Bertram to watch over Jane), and it's later revealed he too is a Visualize member and a probable Rj associate...so there's a fine pattern there. It wouldn't surprise me if Bertram, being either a member or former member of Visualise, is given 'followers' by Bret Stiles or just recruits them on his own terms. Next there's the William Blake poem which he recites to Lisbon and La Roche. This proves how literate and well read he is and that he shares an obvious passion with RJ that isn't very common. Other small notes are he is very well dressed-always in a suit and tie, wedding ring on his left hand, well connected in a position of power, drinks tea whilst sitting with legs crossed like Jane, and is an avid fisherman. In his office there is a fish mug, a fishing ornament and a painting on his wall of the sea. Being a fisherman, GB must be experienced at gutting fish etc and so would easily have the required skills to be RJ. There's also Jason Lennon, his accomplice, who we also know loved fishing.

Then there's the mysterious business of him being all friendly and secretive with the murderer Bob Kirkland. It looks to me as if Kirkland is Bertram's trusted right hand man, his "good friend from the FBI". It's possible he ordered Kirkland to pull strings in order to get updates from Minelli on the case, and then when Minelli refused to cooperate anymore and retired, he took the job as director, so he could continue the spying mission himself. His position in the CBI allows him to give Kirkland the ropes in the Lorelai case. I'm confident he done this because he was worried and needed his best man on the job. He had to keep Lorelai and Lennon quiet, but obviously couldn't risk leading the case himself, or else it would be way  too suspicious.

 I think Kirkland asked Lennon if he recognised him simply because he needed the comfort of knowing that his identity as RJ's right hand man is safe, and that only they know. The line about "hoping that if he were in his shoes, there'd be a friend nearby to kill him quickly too" further indicates to me that he is only an accomplice and meant that if and when Jane catches him, he hopes RJ will kill him before he is arrested or before Jane can torture and painfully murder him. Regarding the Lorelai video, I'm sure RJ guessed the list based on the knowledge he already had and made a provisional video. After killing Lorelai, he probably got Kirkland to break in and make sure it was accurate (could then easily edit any bits he liked). I'm excited however to find out what Jane's plan is regarding the broken toothpick..I think maybe Jane just wanted to get his attention, worry him into making a bad move.

This may prove unpopular but i think at this stage, the least likely suspect is the biggest favourite with the fans, Brett Partridge. People should forget about the voice, because it's not that simple,  most likely Red John uses a voice modifier or else I'm sure Partridge would have been caught by now? Anyway, it makes sense that you wouldn't pick the obvious candidate, from the very beginning, to be your shows main antagonist, but opt to shock the fans with a not too obvious but very viable suspect like Bertram or say Haffner for example. The main thing for me though is the line "if there's one thing I can't tolerate, it's cheap imitations of my work". If you watch Partridge he takes great pleasure in the work done by the imitators, and gets excited by it, not Red John like at all! He just seems too unprofessional. Also, I can't see Red John just standing back and taking insults so easily from Jane, with barely a reaction. Remember he's a showman, an artist, who hates being demeaned by anyone, let alone his arch rival. He has killed for less!
My predictions for season 6 are, we will see the deaths of a few off of the list such as Kirkland and Haffner, and most likely find out who red john is before the characters and then watch on from both perspectives. I also think we might see RJ striking out at one or more of the team members such as Rigsby or Van Pelt, who are both rumored to be leaving unfortunately. In my head I have the perfect ending already (for me)..after a great mental battle of words(or wouldnt it be great to see Jane vs Bertram/RJ play each other at poker, after Jane taught him so well), I can envisage an emotional Jane unable to find it in himself to finish off Red John, but Lisbon steps forward and kills him, after all these years of her saying she's the law, and he'll be tried in court, blah blah..then they can finally be together!
Anyway thats my theory, thanks for reading this! I can't wait till season 6, Sept 29th!!!....most likely I'll be well off, but we'll soon find out! Greetings from bonnie Scotland :-)

After season 5 finale, I watched all the 5 seasons again. I felt like we have enough evidence to know identity of the famous killer RJ. I have been reading the RJ theories almost everyday. Some are quite good but others are too complicated. I think that the mentalist favours simplicity.
I realised that we dont really have any actual evidence.
In season finale, RJ saved Jane. Do we really know if that was actually him? It could have been any of his disciples. If that was in fact him, his voice was distorted. So we have nothing. We cant say its Brett Partridge.
In season 3, Jane was looking for a mole in the CBI. Gale Bertram was introduced in this season. I think that Jane initial instincts were right. He had some weird vide about him. But we thought it was about the case they were working on.
We all have a lot questions about RJ. After some serious thinking, I realised that he was hiding in plain sight.
Gale Bertram is the only one of the 7 suspects who has appeared the most on the mentalist. One thing that I could not understand is why was Timothy Carter in the mall? In season 3 finale, Jane assumed that one the suspect is the mole but what if one of the them was RJ. So when he gave his mole and RJ two different room numbers, RJ figured out his plan. Thats why the assassin went one floor above. This was RJ's plan. Otherwise Jane would have exclude Gale Bertram from his list. Gale was the one who told Timothy to accompany him.
The other reason why I think its him because of the CBI involvement in the RJ case. How did the CBI got the case in the first place? He wanted to keep the case in the CBI so that he knows if there is any progress.
Who has best access to hack the CBI system? It could be Ray Haffner but he does not look like a leader.
I dont know if you guys have noticed this but I believed there is more to the poker game. Lisbon has been playing a lot in season 5 and I suspected that RJ could be one the members. RJ has friends in high places. Have you seen who are the guys playing. Judge, Bertram.... they are all high ranking officials. I think that RJ has been hynotizing Lisbon.
Bertram didnot need any help from Jane to win. He wanted Jane to come and see him. Maybe he had some other plans.
Gale has a coffee mug decorated with fish on his desk and Jason lennon likes fishing. Its a weak connection but maybe there is a story there.
In season 5 finale, Jane never actually said who is on his list except for Bertram who he told Lisbon about. I had some doubt about the list at first but now i believed its legit. But Jane tricked RJ somehow.
I cant wait for season 6. We will finally know his identity.

My theory is kinda far fetched. I mean there is a high possibility that it's not right. But what if RJ is not just one person? What if it's a group. A group of people which each of them are best at something. Maybe Timothy Carter was one of them and after he got killed others continued their way.

Think about it: Bret Stiles is best at manipulating people so he gets people to work for them. Ray Haffner is good with technology. And I think there's an anonymous person who actually wants to hurt PJ. A person who knows about him. He who maybe has a hate in heart for him for a long time. He is the one that kills people in his own special manner. And he is the one that killed Jane's wife and daughter.

Have you read or watched Agatha Christie's: Murder on the Orient Express? don't you think there's a slight possibility that there's not one murderer but a group of them? a group which can turn people. Which can kill people. Which has been described as gentle and kind also as a beast and animal.

You may ask"Then why people who know RJ talk about him as one person?" well, probably the answer is: Because for each of them only one of them is Red John.

I know it's not what you think or what you find possible but if you were kind enough to think about and comment you would make me really happy.

Thanks for reading,
S.H

Just an interesting assumption here. Todd Johnson was a dedicated follower of Red John. It was him who saved Jane in Season 2 Finale. (I believe Red John would use one of his followers well enough rather than show up in person and save Jane himself - he's smarter than that)

Todd Johnson spoke 'Tyger Tyger' in his last hours to let Jane know it was him who had saved Jane. After Todd Johnson was caught as the cop killer he knew he was going to serve indefinite jail time. He had to tell Jane about how he had saved him and try to make his sentence easier. 

O'Laughlin came to know this and burned him alive before Jane arrived or before Todd had revealed anything related to Red John.