Red John is Ray Haffner.

Lorelei Martins said her sister's death set her free and brought her to her full reality. Do you really think she would hear deep thoughts like this from silly Smith or Bertram or the sheriff? The only people who can teach her these kind of things are Stiles and Haffner. She was an intelligent, beautiful woman, she would not have been attracted to anyone else but Haffner or Kirkland maybe. (the same goes for Rosalind and Kristina Fry - just imagine them with Haffner, nobody else comes close)

And there is the voice. We know Red John speaks in a gentle, soft voice, more people confirmed it. Do you really think when Red John spent months with Rosalind, he had a 'thingy' with him everytime he talked to her? (don't know what the thing is called that changes the voice). Haffner has a soft voice, so did Kirkland but none of the others do.

And then there's Sophie. She seemed to think he was an interesting, pleasant person who is hiding something. Just imagine Haffner talking to her; he is the kind of person who would hold back a lot of things while still being pleasant and nice.

Sometimes there's no need for complicated theories because everything's simple.
He has short straight hair, he is not thin and not too muscly, he is the right height, he and Patrick or not friends, etc..

Haffner is Red John.

This is more a series of observations on the current season than a theory.

I have always been a fan of the show. The Red John mystery has kept us engaged for so many years because clues have been released slowly and poignantly. The current series has undermined that system, by throwing  a blizzard of half-baked clues and red herrings at us to the point that each of the names on the list of seven (and at least three not on the list) could be Red John. After such a slow, laboured and brilliant build-up, things suddenly feel rushed and careless.

The joy of the show was deduction. A quick look at the latest theories posted on this site shows us how far this series has removed itself from that. We are now left to suspect the likes of Michael Kirkland- a character of which we had no knowledge up until a few weeks ago. This isn't crime-writing at its best.

The Tiger / Tiger conspiracy has been a let-down of epic proportions. For me, the scene in which Reede Smith utters 'Tiger, Tiger' to the prison van driver who immediately repeats the words is the worst in The Mentalist's history. I literally didn't know whether to laugh or cry that all of the subtleties of the past seasons had been reduced to a such a farcical conclusion.

I will of course keep watching and really, really hope that Heller and the team manage to pull this series back.

Ugh I am just going crazy with this show. I'm obsessed!

So the house that they are swarming in the S06E07 promo is in Roseland, California (you can see the police cars). Roseland is very close to Napa Valley geographically. Are they at Sheriff McAllister's house? Might be a stretch, as they may just be at another crime scene that they usually have week to week. Although, we've been told (by some of the actors and Heller himself) that the next few weeks will move at a very high-pace plot wise, and so I'm assuming the next episode will only have to do with RJ and the fallout from last week.

Additionally, in the promo, when Rigsby is talking to another agent telling him about RJ and the bomb, we can see (in the HD version) that the board has 3 suspect photos, Haffner, Stiles and McAllister. He looks to them in reference when explaining that RJ apparently brought the bomb to kill 'the suspects.' Since Smith and Bertram are not there, does that mean they are deceased? Also, the diagram on the board has the bomb explosion point marked down, it also has post-its where DNA was found (in 2 places-- maybe more, it was too blurry to see-- that coincide with where Jane had the 5 of them positioned in the room). Interesting to note.

One thing is certain... I spend A LOT of time thinking about this show. Oh boy. I am starting to worry that Heller's version of events to come won't be as fascinating or plausible as some of us have theorized. I really hope that's not the case. I am also expecting full explanations for all the clues that we have been given (for example, the 'he is mar'). Let's cross our fingers that Heller will blow our mind with the episodes to come!

LOL after reading all these different theories which each person wanting Red John to be so and so, and saying they would be dissapointed if Red John were someone else, I really feel sorry for Heller. He has hyped Red John up so high that honestly, there is no way he can end this series without lots of people being dissapointed

Okay everyone is saying that Bertram is Red John. And he probably is, but I was just watching Strawberries and Cream, season 3 finale, on TNT and Jane and the team were trying to uncover who Red John's informant was in the CBI, by telling them were Hightower was. All of you most likely watched the episode so I am not going to go into details. They gave every suspect, including Bertram, a different room number. So when the assassin that the informant hired came into one of the rooms they would know who the informant was. It turned out to be Craig. :(
 But if Bertram is Red John, and lets assume Craig was in contact with him about it, wouldn't he have known that the room numbers were different and that it was a trap?

I thought about this for a while. But then I looked at the other two suspects, and realized that Bertram is the better choice to be Red John. Because, come on.
 
And to the people out there who think that Red John is Bob Kirkland's twin brother Michael, though some of you do make very valid points, let me ask you this. Would you really be satisfied with Bob's twin, whom we didn't even know about until about three weeks ago, being Red John? I know I wouldn't. I really hope that Red John is Bertram.