We don't have to look any further than Brett Partridge to know that he is Red John and I'll attempt to cross the other suspects off the list to prove it. Bare with me please

Gale Bertram- remember back in Season 3, when Patrick come up witha clever scheme to reveal Red John's mole in the CBI? well Gale was a suspect then too. If he was Red John wouldn't he have sent the assassin to the apartment number he was given rather than have O'loughlen send the assassin to his apartment number he was given? And if he was Red John he would have quickly figured out it was a ruse based on the fact that O'loghlen got a different room number than he. Red John didn't dicover it was a ruse until after Van Pelt told O'loughlen about the whole situation. So that's Bertram off the list!

Bret Stiles- based on evidence from both the Rosland Harker and Sophie Miller, it's safe to say good ol' Visualise leader Bret Stiles is too old to be Red John! However, I do indeed believe the theory that Bret Stiles is the father of Red John. He is also

Reede Smith- According to Sophie Miller's evaluation, Reede is too obese to be Red John.

Thomas Mcaslister- According to the latest episode of the Mentalist, it is revealed that Mcalister does not suffer from Vertigo. Whereas it is previously stated in the episode prior that Red John most ceratainly does! However, this may be considered illegitmate. (honestly I wouldn't mind seeing him as Red John.)

Bob Kirkland- If Kirkland was Red John then why in the preview for the next episode (Red listed) is he literally torturing Jane to reveal the names on the list of Red John suspects an less he is NOT Red John. Kirkland is far too obvious and the fact that he was introduced in season 5 really puts doubts in my mind, its far too late in the show. I honestly think he hates Red John and also has and agenda against him. I'm calling it now, that he'll probably be killed in next Sunday's episode. (God forgive me if i'm wrong.)

Ray Haffner- Ray is my second choice for Red John, if Partridge is indeed dead. Crossing Haffner off the list is difficult so i'm only going on minor clues. Bare with me. He is two inches too tall to be Red John and he was introduced in Season 4! like Kirkland he was debuted too late! However, I know that is not a lot to go off.

So too sum it all up, Red John is notorious for quoting William Blake's famous poem Tyger Tyger. William Blake also painted a picture titled a "Brace of Partridge." a coinsidence? I think not!
Rember the simple soloution is the usually the correct one.

Spoiler-alert:
Have a look at the Actor, who is playing a "young man" in the episode "Red John".
http://img5.fotos-hochladen.net/uploads/youngman8b3i47fdzl.jpg

Striking similarity with one of the seven suspects, right?! ;)
I bet he is playing RJ in a flashback to 1988 and the visualize farm.

Did you already watch the third episode?

It is very unusual that Sheriff doesn't want to climb the ladder and than walk closer to the edge of the cliff at the beginning. It's like Heller is throwing him at us. But than again, at the end of the episode he saves Patrick from falling from the roof, so his fobia of heights clearly doesn't exist. We can now officialy say Sheriff isn't afraid of heights.

But than just when they walk down from the roof, he gets scared of a few pigeons, yells for a second and than says: "I didn't see that coming, I hate those things!"

That is probably the biggest hint in the episode. Sheriff does not like pigeons! And as we found out, Patrtridge could be taken as a synonim for pigeons, so there could be a possibilty Sheriff had something to do with the death of Brett, or at least Heller wants us to think that way.

I honestly don't know who could be Red John. Heller has that mystery well wrapped somewhere in there, but is constantly throwing us fake hints to throw us off, when we're trying to found out.

Truth is, Mr. Heller is a very fine mentalist and a manipulator himself and he is also one step ahead of us, just like Red John seems to be one step ahead of Patrick.

I think Patrick wants him to feel that way, but he knows clearly more than he is sharing with us or Lisbon.

Next episode with Kirkland is going to be very interesting. If I judge from the promo, Kirkland indeed isn't Red John himself and is just trying to catch him himself or works for him and is paid to scare Patrick.

Oh, and also, I don't think Heller is such an amateur to let us now from the cast appering in the episodes, who Red John is. If Redee Smith is going to be in the episode 8, than that's because Heller wants you to think he is RJ. Just like last week, when he threw Haffner at us and this week Sheriff.

I don't believe Red John is one of the 7 suspects, but every single one of them is connected one way or another with him and has a specific interest connected to him.

Who else thinks that Jane should practice on using guns or learn some form of self defense seriously what is he going to do if he faces red john alone he won't stand a chance

Patrick Jane is not Red John. Bruno Heller has said so in an interview. :)
http://insidetv.ew.com/2013/05/06/mentalist-finale-season-6-red-john-list/