Rigsby is Red John & has seduced Van Pelt to be a follower.  I imagine the real manipulation occurred after she killed her former fiance.  He is good looking and charismatic enough to manipulate, especially after forming relationships.  He has always been the supposed dumb/nice jock of the group to hide his true diabolic mastermind nature.

Under this theory:

1.  It meets the Keysor Soze theory, because no one would suspect Rigsby (too nice, naive, second fiddle to Cho, etc).
2.  Would meet the amazing reveal criteria, because it reveals not one, but two members of Janes CBI team as villains.
3.  Rigsby fits the physical criteria.

Just had a thought when posting a previous theory -- Bertram, McAllister and SMITH were all standing together when Jane made them get up against the wall.

So, how did McAllister die if Smith and Bertram didn't? McAllister has to be alive!  OH my I wonder if that means he's RJ?

Not what I wanted to see, but he was there from the beginning.

The name THOMAS has repeated throughout the show with different characters.  It means TWIN

Bertram used the name THOMAS when opening his storage/safe place.

Ok, so, firstly, for all of those people that think Red John is Bertram:

- it  would make sense, but it is definitely too obvious for it to be him because the mentalist is known for it's plot twists.

- and if it was Bertram, then at the end of season 3 (Strawberries & cream) then the assassin sent to kill hightower would have gone to the room that they told bertram she was staying to find the CBI Red John accomplice that burnt Todd Johnson alive (granted, she did go to that room but it was only so she could climb to the other room with the rope). as Bertram is part of the Blake association, then the assasin could've been ordered to check both rooms for Hightower, this one was just a mixed up thought that i haven't described well haha.

but i think bertram is more than just a tool for red john, he is closer to him.

so, i think that if red john is anyone on the list, then sheriff mcallister is red john because:

Firstly, He is alive, and one of the bodies found after the explosion wasn't him. Say he is red john, then he wouldn't bring a bomb into Jane's house without a backup plan. He is cleverer than that. So he makes the world think that he is dead in order to draw away the suspicion that he is red john. Also, an interview i read somewhere, went something like this:

Interveiwer: so are we sure that those three died in the fire? and it wasn't a trick/plot twist?

Writer: well, yes, is was real bodies in that house, but there are some surprising turns coming up regarding the explosion.

notice how he dodged the question and gave it away a bit?

-in last nights episode (The Great Red  Dragon) Bertram went to a vault storage room thingy by the name of Thomas (which i think is Sheriff Thomas Mcallister) and my theory was confirmed when there was wine bottles in there, because Napa is the wine country!

So you may be thinking 'say that is McAllisters Storage room, that doesn't mean he's Red John' 

well, there are several reasons why this could mean that he is Red John. Firstly, he could've contacted Bertram and asked for a favour (which he had to do as part of the blake association) to go into his storage and get passport, money etc. and plant the fake lighter USB stick with a code message, knowing that jane would solve it (i suspect it told him to meet him in the church because jane doesn't believe in God so why would he go to a church, and he wouldnt just let go of the RJ investigation like that after 10 years of devoting his life to it, so just told Lisbon he was giving up for the same reason he left her by the sunset and drove off in 'Fire and Brimestone')

And also, if you look really closely, after Bertram opens the box in the storage room, when he lifts out the straw-like packaging first, i think you can see that buried in the straw packaging, there is RJ's signature knife (the weird shaped one RJ is seen holding in many scenes).

so yeah I guess thats why I think it's Thomas McAllister

Also, does anyone have a theory for why there are pigeons emphasised in loads of scenes (the scene in the house where partridge was found dead, in the promo for 6x08 on the angel made of stone in the church and various other scenes)

This is probably all wrong but thank you for reading and feel free to comment! :)

Pro/con

BERTRAM - No way, if he was RJ hey wouldn't want us guessing about it only to reveal that, yeah he's still RJ in episode 8. He also wouldn't kill PJ while PJ is unconscious in the hospital. Also all his actions in ep 7 show a defeated man on the run...not RJ the worthy adversary. PJ would not out him in the press. PRO - There are really no pros left for him at this point.

REED - Lets all agree he's done.

PARTRIDGE - PRO- True we never see his face in morgue and technically Lisbon never checked his pulse when she watched him die, maybe its bad writing and they allow two top detectives (Cho/Lisbon) make rookie mistakes. Also, the cut odd tattoo is interesting. Finally, so many things rule out all of the other 6, that I have to acknowledge that they may even be so un-inventive and unoriginal as to have the killer be the creepy forensic guy cliche (Law and Order SVU, Bones, NCIS, Dexter, etc.).

MCALLISTER - PRO - Promo really seems to show him being alive when presumed dead. Wine storage lady calls Gale Bertram "Thomas." Promo makes us think He is being chased. Has been there from the beginning. After Hafner, he most closely matches Rosaland/Sophie descriptions.
CON - If a promo sort of "tells" me the answer to a mystery I automatically assume it is misdirection. This is a huge blow to me believing McAllister could be RJ.

HAFNER - PRO -  Fits RJ descriptions better than any of the others. If McAllister is alive, seems that others from the house could be too. What the hell happened in that house..gunshot...?
CON- Seems he's dead. Maybe one person faked death in that house, but there has to be somebody or two dead in there. Seems more likely that the BLAKE side of the room was the safer side of the room to be on for faking death while surviving. 

STILES - CON - Same as Hafner, PRO- Seems too grand a character to have a mundane exit and seems odd that the Visualize angle would be closed now with him and Hafner dying.

KIRKLAND - PRO - Outside chance he looks like someone in the church (via stills from the promo). He's creepy, and the whole possible twin brother theories seem to have some interest, especially since strong cases can be made to eliminate the other 6 suspects. CON - We saw him die badly and the twin thing would be tough to weave in in just one episode without it being sloppy.

EPISODE 7- PRO -  I can completely eliminate Bertram and Smith which I couldn't do before EP 7. 
CON - I am much more confused about who of the other 5 it could be...