Red John must have been working in Visualize farm in 1988 while in his teens or early twenties. Red John must have the physical power to hold and bind and slit them. He cannot be Bret Stiles or Gale Bertram or Sheriff McAllister, they're too old; it isn't Partridge, he's too young. There's also other reasons against them.

Gale Bertram cannot be Red John because if he was Red John then at the end of 3rd series when Jane's team informs the five suspects of Hightower's place with fake room numbers then O'Laughlin would have one number and Bertam another so they would know about the scheme and wouldn't act upon it; also Bertram needs Jane's help in playing poker and is genuinely frustrated at his loss.

Bret Stiles is miserable when he thinks that someone tries to replace him in Visualize and needs Jane's help; He cannot be our super-genius killer.

Partridge is in one occasion easy to judge a murder scene as a classic Red John and is pissed off when Jane finds out. If he was Red John he wouldn't have been so obsessed to underestimate Jane's skills in identifying a Red John scene.

And about the Sheriff (Thomas McAllister) and the FBI agent (Reede Smith): wouldn't you think it would be hard for someone in their ranks to pull off a charismatic character of a leader who is able to easily affect people like Kirkland or O'Laughlin? Certainly not; and again Reede Smith is a little younger to be our guy and a little less sophisticated, it seems.

And about Kirkland: the first time that Jane meets him and shakes his hand is one episode before Lorelei tells Jane that she wonders why they didn't become friends the moment the shook hands. This strongly implies that this hand-shaking has happened long time ago not the previous episode; after all she wouldn't expect them to become friends in one episode!

So who remains? Haffner.  I have reasons against him but also for him. He's a member of Visualize so Stiles information on Red John can be justified but the fact that Jane easily gets rid of him in "Little Red Book" doesn't strengthen our suspicions. So I'm not sure but he's the most plausible suspect. If not him then it's Reede Smith. It sure sounds a little pathetic and cheap but I realize that my reasons againts him are not as strong as the other ones.

After seeing the prevue photo for episode 1 of Season 6 with Jane and Lisbon and Bret Partridge standing under some kind of a tent, I have changed my mind about Partridge being Red John.  He may be a disciple of RJ, but  his slouching stance and standoffish personality, in my mind, could not attract devoted followers.  I now think that Ray Haffner has more of the right kind of personality to be RJ.

I've posted before, you can see my theory here: http://www.whoisredjohn.com/See-a-theory-Red-John/4185

I've used Rosalind's description before, but lately I've been thinking why hasn't Jane himself taken it into consideration? He has boiled down his list of suspects to only seven suspects based on what? well definitely Rosalind's description is not one of them, otherwise Bertram wouldn't be on the list. So I can respect those who doubt Rosalind's description. But some folk say stuff that are downright nonsense, like it wasn't Red John who saved Jane in the second season finale, or that Red John is not a person but an organization, or Red John is Jane. If you're going to be skeptical of everything then there's no point in constructing theories, since there's no data to back your theory. There are some facts we cannot deny, like Red John being somehow connected to Visualize, or him being a charismatic leader.

Despite all this I still think it's Haffner. Think of the suspects in terms of a scale from the most expected to the least expected. My experience tells me it's always someone in the middle, someone most people wouldn't think of so that the show can preserve the element of surprise. On the other hand it shouldn't be disappointing either. The best choice for the middle suspect is Haffner. Just think of it for a moment. Think of the person Rosalind, Miriam, Rebbecca, and Lorelei fell for. Think of the charismatic leader who gave orders to Todd Johnson, Craig O'Laughlin, Timothy Carter, Jared Renfrew, Sheriff Hardy, and possibly Hardy's father. Think of all you know about what he's done. This blank image you've been imagining since the first season doing what he does, replace it one by one with the seven suspects. Trust your gut feeling, who's the guy that fits this image? For me it's Haffner. I challenge you to go through all this and still claim it's Partridge!

Why does everyone think that Rosalind's description is true? Red John could have easily manipulated her to give  a wrong description or she could be a disciple of Red John. Everyone thinks that she is innocent just because she is blind!!

I don't think that we should eliminate suspects just because of their height, hair or voice. How would we even know that it was RJ that came to save Jane at the season 2 finale? It could have been any of his disciples including Timothy Carter.