I think Red John is Ray Haffner of Walter Mashburn because they both like Teresa Lisbon and this is why she was not killed in Episode 1

Writer:
Tom Szentgyorgyi has written or co-written 12 episodes.Most of the episodes are significant and focus on Red John. He wrote the first two episodes featuring Haffner. [He also wrote the origins episode with Kirkland, but I believe Kirkland will no longer be a suspect after the upcoming episode.]

Tyger Tyger:
The poem is about an unimaginablly evil beast that was created. RJ is the beast.
Visualize is the creator. Haffner is a member of Visualize and has been
ever since he was a
teenager when he was a maladjusted and distressed boy.
He insists the cult helped him.
Visualize, likely unknowingly, helped Haffner become a well-adjusted serial killer.
[Probably just a coincidence: The poem was written by a British author. There's one British suspect.

Lisbon:
Haffner and Lisbon have some sort of past, which could be nothing unusual, but could be RJ trying to get close to the closest person to Jane.

Psychiatrist's Profile:
Haffner and Kirkland are the best matches for the profile.
Reed is a stretch since he is not very fit.
Stiles, Bertrem, and McAllister are too old.

Sophie Miller said he can whistle.
And when Ray Haffner went to the hospital to see Lisbon he was whistling while leaving the room.

Check them out

http://www.spoilertv.com/2013/10/the-mentalist-episode-606-fire-and.html

http://www.spoilertv.com/2013/10/the-mentalist-episode-605-red-tattoo.html

haffner is red john he would be a great red john.

kirkland is so dead this episode....

does anybody knows if this would be the last season and how much episodes will have? thanks from Peru!

ok , let me start this off by saying many people probably understood heller wrong when he said the suspect was on the list .. because this is what happened:- "Heller can we trust the list" ...
answer:-"yes we can trust the list" .. you guys know how bruno .. even if the list is fake he can't just say that straight up.. My guess is the list is real but with 1 or 2 extra suspects jane has saved in his mind .."Just incase" now let me get back to "What if red john is on the list" , Let me start excluding suspects using completely logical and reasonable arguments , we know that Red john himself went to sophie miller as Jay roth, Back then Brett stiles was famous and too high profile to risk being identified by sophie miller.. secondly he did break out Lorelei martins out of prison , red john would of never done that unless he wanted that to happen.. which he didn't , Ok so brett stiles out , Brett partridge Assuming he is dead which he probably is.. is out aswell , Leaving 5 people , Kirkland goes down the drain in a heart beat because of the season 3 episode 4 promo.. #1 ..torturing jane for the real list of suspects which red john already has..  , #2. he broke into janes room and stole his info while red john knew the list way before ,, 
Now we have 4 suspects left ,,, Lets try our best to exclude 2 more , Gale bertram first... Gale bertram as the director of CBI is too high profile to walk into Sophie millers office just pretending to be someone else.. secondly he doesnt have the correct physical features and seems like he doesnt have the correct charisma... now we can't really exclude reede smith out of anything but i just  will go with my hunch and say hes too shallow to be red john....

Now we're left with 2 people .. Sherrif thomas mcallister .. 
                                            Raymond haffner

Now the sherrif would make a good red john because of one thing , The actor Xander berkly has been the criminal mastermind of the show nikita and is a very skilled and talented actor and many clues were represented about him in season 6 episode 3 ... "His stealthy movement, the fact that when red john saved jane and came back to scare him he moved quietly.. secondly..  he saved jane on the roof top , could that be a sign , that red john saved his life twice?...  thirdly his pointy shoes .. when rj saved jane from the copy cat killers he was wearing pointy shoes aswell... theres the scene when he freaked out from the pigeons oluaghlin asking van pelt to come to napa county...him whisteling.. etc etc

Haffner also suits because of some clues such as him liking Teresa Lisbon and him being from visualize , having money , being charming and yet creepy at the same time... Also one scene where he asks cho "Who do you think is smarter , me or jane?" cho says definitely jane.. Haffner then has the creepiest smile on and walks away as if thinking if hes smarter he would of caught me by now.... 

Anyways thank you guys for reading this long ass post hope this has helped you out i can keep going on and on and on on possibilities outside the list and interviews with heller and etc etc let me know what you guys think in the comments and  Feel free to ask any questions , thank you and bye bye

OK this isn't a betting game but here's my conception of the odds and a couple of thoughts. 

Ray Haffner:  15% chance  - overall a strong fit but not a knockout in terms of being an exciting ending because he's just not that great of a villain. Likes Lisbon so he will be be punished. (This is basic TV psychology)

Walter Mashburn: 15% chance - Good villain and remember, he had sex with Lisbon so he's got a big payback coming. Maybe in "He is Mar" the "r" is an incomplete "s". His odds would be a higher if he were on the list of 7 and if we'd seen him in episodes more recently.

Multiple people: 15% - "He is Mar" could be an incomplete "He is Many".  Kind of a cop-out but fits what has been going on. This would maybe leave room for the storyline to continue in the future.  If this is the case, then Stiles is heavily involved.

McAllister: 10% chance - Smart guy, cagey, and seems pretty creepy in a restrained way.  Plus there's extra points for being with the show from the start, because the writers would want to have a go-to guy in case they need to wrap the story up.

Brett Partridge: 10% chance - It would be pretty bogus to pull a zombie trick but as PJ says, anything can happen on TV. Plus he gets points for lurking since the beginning.

Kirkland:  10% - Evil as they come but not a cult leader and incapable of seducing LM. He sure looks like he had a face transplant though.

CBI Ron: 10% chance - A somewhat hokey choice. He'll need some character development real quick to be viable. But potentially an appealing lurker character.

Reede Smith:  5% chance - Likes cold weather because he's fat. This clue fits but many of the others don't, and he really doesn't have much prominence or character development yet.

Bertram and others: 10% combined.  Bertram can't win at poker, and he doesn't seem like that strong of a villain.