I`ve changed my mind again. I`ve decided to create a theory based on how Red John is (how I think he is based on the evidences), and I think this will make sense for you, too. 
We all know that Red John`s major satisfaction is when he murders his victims, when he sees the life getting out of them. Still, I think that now Red John also has another big favorite hobby: seeing Jane feeling destroyed by RJ`s murders, and by the fact the he still is there, watching him with every step he makes. So the question that comes up is: Who is the person that is almost always there when Red John kills someone? Who is carefully analyzing the crime scene, waiting for Jane to come? Right, Brett Partridge. Is him, guys, I have no doubt. His voice, his look, his way to be, the way he looks at Jane, the way he says his name. This guy is sick. 
In a show like this, any detail counts. So have you noticed that Brett Partridge has change his look A LOT? I mean, in the first season he looked like a loser, and now he has a cool hairstyle, and he dresses in a different way, more stylish. Could this be a clue? Yes. As Red John becomes more and more shinny, so does his alter ego, Brett Partridge. I`m not saying he has multiple personalities, I am sure that he is 100% aware of his actions, but I think Brett Partridge`s evolution is determined by Red John`s.
If you think about it, in the first season neither Brett or Jane couldn`t stand the idea of being in the same room, and now, in the fifth season, they seem more..."friendly". I`m pointing this because we know that RJ sees Jane as and "old comrade, rather than an enemy" (Lorelei) and I can see that Brett`s behaviour with Jane has changed. If in the first season he accuses Jane of messing around and being a clown, in the last episode of season 5 when Jane strangely asks him if he thinks the murder was made by RJ or not, he answwers "I am just guessing. You are the expert". What a change of attitude, huh?
So this is it. All I have said before, plus the most important clue - his voice, which is exactely the voice RJ puts when talking to Jane, lead me to the conclusion that he is the one. Brett Partridge is Red John. He has to be him.
Fun fact: I have a friend who doesn`r watch the show, so she has no idea what it is about.I`ve decided to make an experiment, so I asked her to listen Red John speaking. Then I asked her to listen to all the seven suspects speaking. When Brett Partridge voice started to play she told me "I`ve listened to this one before. Is the same voice as Red John`s". 

It may sound awkward, but if you go back to that episode when patrick is captured by 2 college guys whom think they're RJ, you'll reconize the voice of patridge reciting the poem of the tiger...

I don't have a lot to add to what's already on here but I feel like Brett Partridge is the most likely - probably unlucky with women so acts out a hatred, we don't know much about his past, just generally a bit creepy. But I have another question. If Rosalind Harker has met, and of course talked to, Red John, can't they play her a tape of the 7 suspects speaking? He could get interrogation tapes from most of them, record Brett Partridge at the next crime scene, play one of Brett Stile's speeches etc. I'm assuming he spoke to her in his 'normal' voice as who would help out somebody who spoke in Red John's creepy voice!

my theory for who is red john is may or may not be Brett Partridge, but he meets some of the criteria of the serial killer. In the last episode of season two, patrick jane encouter red john who is wearing a mask, but it may not be red john, if it is red john we can see he is male in his late 30's because in season 5 we found out red john started killing in the late 1980 when he was still a young man and now we can assume he is a slightly older man in his late 30s to early 40s and was a member of visualize. He is also able to manipulate people mostly women who have sleep with him so he can be rather handsome and a lady killer. So we can eliminate Bret Stiles and Sheriff Mcallister because they're quite old and may not be able to sexually active. We can also eliminate Reede Smith because he is too fat because as you can remember in the last episode of season two red john is a slim figure who has a rather raspy voice. So it leave us with three suspect for who is red john it can be Ray Haffner, Brett Partridge, and Robert Kirkland. But remember what color is red john eyes in the last episode of season two.

Don't know, but here is some Brett Patridge for teh lulz.

I write this post in the hope that I might be able to shed some light on many of the great Mentalist mysteries that prevent us die-hard fans from experiencing a proper night's sleep. I'm just going to jump right in.

First of all, I will address the ever popular list of 7 suspects. Bruno Heller (creator of the show) is quoted saying these exact words when asked about the list at the end of the season 5 finale..."Yes, we can trust that list. As much as much as Red John has been one
step ahead, Lorelei Martins’ intervention changed the game. So as much
as Red John is trying to play from a position of strength in reality
Jane has gotten a lot closer." ...well snap. There it is. I don't know about you but I'm going to trust that list. Then, I started thinking. Of course we can trust that list, even if Bruno was never quoted saying those words. Think about it. If Red John gave Patrick a DVD with a list of 7 names and his true identity wasn't on the list, wouldn't it be obvious who Red John is? If PJ had heavily suspected somebody and RJ didn't put that name on the list, then he just gave himself up! The ONLY way to truly disguise himself was to name himself among the 7. Like Bruno said, RJ is attempting to be clever and play from a position of strength but in reality PJ has him narrowed to 7 names.

Now I am obligated to discuss the "funny business." The "wait, maybe Bruno Heller is tricking us" areas in the show. I have heard so many theories about Lorelei still being alive, about Lisbon being one of RJ's accomplices, about Patrick making the video of Lorelei and the 7 suspects himself. I feel very confident that the list is very very real, made by RJ himself, that Lorelei is very very dead and has been dead, and that Lisbon is most certainly not one of RJ's accomplices or disciples. My reasoning: The video was most assuredly made by RJ because it was given to Patrick by that one lady (RJ's accomplice that stole the baby in the season 5 finale). PJ would have absolutely no reason whatsoever to make the video himself. I mean, after showing Lisbon he crushes the disk. Nobody sees it other than her. And it CERTAINLY wasn't made by Patrick to show Lisbon (like some theories suggest), because Lisbon is not an RJ accomplice. NO NO NO. That would kinda ruin the show because a major storyline in the show is Lisbon and Jane slowly falling for one another. So the vid was definitely made by RJ and Lorelei died when the show says she died. No funny business there.

Here is where it gets interesting. The show is predicated on "clever tricks" and "explainable solutions," not magic and mind reading and that sort of thing. So there will for sure be a logical explanation to how RJ did what he did. Here is my theory: Obviously, Red John knows that PJ is a smart guy. When he found out that Lorelei had told PJ about the hand shake, he knew PJ was gonna make a list. He knows that PJ is clever enough to narrow that list down to people that could ONLY be Red John or a RJ "disciple." I think that the list of seven names includes all of the RJ disciples that PJ has met and RJ himself. So 6 disciples, 1 Red John. This would be really easy for RJ to work out. He simply asks his disciples "Have you ever met (shaken hands with) Patrick Jane?" If they say yes they go on the list, if they say no then they don't. He got 6 disciples that said yes so there is your list, the seventh is RJ himself. He knows that PJ is smart enough to narrow that list down to only possible Red Johns, an lets face it, if you can possibly be Red John then you can possibly be a disciple of his. But PJ doesn't even know that that is what he has done. Am I making sense?? This theory would make perfect sense because every name on that list is sorta suspicious in some way or another. I'll go thru the evidence.

Evidence:
Ray Haffner; He had the whole Visualize weird moment with Lisbon. He doesn't seem smart enough to be Red John, but we got a look into his past and his membership at Visualize so I'm thinking disciple??

Gale Bertram; We know he has quoted some of William Blake's work in previous episodes. PJ also said that Bertram gives him "weird vibes" and when he first met Patrick he referred to him as our "boy wonder". Also, obviously his relationship with Kirkland is freaking suspicious. He doesn't seem smart enough to be RJ however. So, I'm thinking disciple??

Bret Stiles; Never know with this guy. Being the head of Visualize is certainly 1 strike against him and he's had numerous suspicious moments throughout the show. Always seems to know something about Red John and what he's planning. Smart enough to be Red John but I just donno. Definitely a possible disciple.

Bob Kirkland; Such a shady character. Holy moly. I don't like that he has come into the show so late and seems so Red John ish but you can never be sure. Everything he has done points you to RJ but I donno if he is in fact Red John. I think he was a big part of the "happy memory" somehow but I'm not even a little bit sure about that. Definitely could be a disciple, definitely.

McAllister and Smith; don't have too much to say about these dudes. We know that Patrick has met them so that is probably why they're on the list. Because they are RJ disciples that PJ has met. Simple. 

Brett Partridge; For some reason, this is my pick for Red John. I just can't quite explain it but every time he shows up all i can think is Red John. What I just can't stop thinking about is how Brett's first words on the show were "Red John enters here." Sent shivers down my spine. Also, in the season 2 finale, Partridge and Jane meet up early in the episode at a crime scene and Jane "scares" Brett (hard to explain I hope you know what part I'm referring to). He leaves the room and then walks back in and scares him. Later in the episode, Red John saves Patrick and then after reciting the Tyger Tyger poem scares him. Hmmm...interesting. I want to hear your guys' thoughts!!! :) Sorry for the lengthy post lol. 
 

okay
in the season 3 final, when pj kills timmothy carter ("Red john")
there is a man in a red sweater sitting also at the mall..http://www.youtube.com/watch?v=590v4FCm6WU
this man might be Robert Kirkland...I really do not think that bob is rj...but what did he do there?...