Before this episode I was convinced that RJ was Haffner. However, Haffner's conduct in this episode was what I would expect RJ to be. He was quite angry and foolish, you would expect RJ to be calm and collected. This got me thinking about all the other suspects and this is what I came up with:

Ray Haffner: Was my prime suspect. He fits the descriptions perfectly and is of the right age. He is also a member of Visualize, who IMO will be key in finding RJ. Also he isn't in the law enforcement unlike the other suspects (except Stiles). However, as I previously said his behavior doesn't look like RJ's. He has a fear of spiders, we might have all misheard Sophie Miller's tape and also she she isn't sure if the "fear of heights" is actually his true fear.

Gale Bertram: He seems to be a member of the "Tyger, Tyger" group, which IMO rules him out as RJ. He also doesn't seem to have the character of RJ, he asked for poker lessons from PJ- would RJ do that? I don't think so.

Reede Smith: Its safe to say that he isn't Red John but is part of the "Tyger, Tyger" group. I reckon he will be killed off in the next episode.

Bret Stiles: Too old to be Red John and doesn't fit the descriptions at all. Also if it was in fact RJ who killed the PI in the latest episode, I doubt Stiles would be able to overpower the PI so quickly, he is rather old after all.

Thomas McAllister: To me he seems like a prime suspect now. Remember when RJ saved Patrick and shot the people who were holding him? That was some impressive shooting by him, especially the one in the knee cap. Now think about when McAllister saved Patrick at the top of the chapel a couple of episodes ago. Great shooting again. Some people also pointed out that RJ and McAllister wear similar types of shoes. I also reckon McAllister might be scared of heights and the only reason he got on top of the ladder was to save Patrick. He wasn't going to let some low life take Patrick away from him, after all RJ has been messing around with Patrick for about 10 years now- all that effort for some random guy to shoot him? If you are scared of heights it doesn't mean that you can't climb a ladder if you really have to. Furthermore, people who are saying that McAllister is too old, apparently he is supposed to be about 45 in the show, fits the age pretty well I think. He is also rather calm and clever when Patrick is around (unlike Haffner), he tells quite a lot just by looking a a dead body- almost as much as PJ. now the only catch is that McAllister was sat with Reede and Bertram in the office and he obviously knew something, so does that mean if he really is RJ- he works with the "Tyger, Tyger"? Or is he trying to infiltrate them like someone on here suggested.

Bonus: http://www.youtube.com/watch?v=3Pxzpl9BOoI this a promo for the next episode. Now I might be reading too much into this, but just look how Haffner and Bertram react when PJ pulls out the gun. Haffner especially looks like he is about to shit himself, RJ wouldn't react this way would he? RJ would have known this was coming. Reede on the other hand is rather layed back and is almost smiling, weird. We also get a quick glance of McAllister (before PJ pulls the gun out), he seems the most chilled out one there, cross legged, almost as he knows whats coming next.

Thanks and tell me what you think please

Haffner fans, I hope that after the last episode you don't seriously still think it's him? :D

How unimaginative..

I think Heller had this all planned out perfectly. All red herrings are so perfectly thrown to you, you just have to bite. But I didn't!

Look. You have to admit Heller is a step ahead of us, for a reason. His aim was to suspect Haffner at this point, of course.

Everyone is so concentrated on the Sophie Miller's tape. And yes, this was a huge trap. This acrophobia acarophobia thing. That's the trap I'm talking about. Jane explained Lisbon that's a fear of heights and we clever guys figured out, it's actually a fear of bugs and now when we saw Haffner got scared of a little spider, we're all smart, cause we think we solved the case.

No we didn't. Sophie Miller wasn't sure about Jay Roth's phobia. This is Heller leading us into thinking Sophie got the phobia right, when clearly she put her options open and wasn't sure. And we yet blindly believe she is some mastermind who can see everything straight away.

If we can indeed trust RJ is on this list, I still think it's McAllister, cause he is the smartest of all the suspects.

So we know a few things about Red John.

1) According to one thing I read, it won't be until November 24th that we actually know the name of the real RJ.

2) RJ was "young" back in 1988.

3) He at least had a full head of hair.

4) He's 5'11"

5) Muscular build.

6) Left Handed

7) Afraid of something

8) Fans will be disappointed by who he is.

9) Can whistle.

So here is why I think it is McCalister:

1) His character's stated age is younger than the actor who plays him which I find odd.  He is listed as being born in 62 or 63.  That would make him 25 or 26 in 1988 ... young enough to be the guy.

2) Right height, build, handedness, whistler.

3) He was introduced the earliest of all of the suspects on the list (season 1, ep 2). Given that RJ was the focus from early on (at least PJ's motivation), it seems likely he would be a character since early on.

4) Only one of the suspects who seems to surprise PJ.

5) Straight hair even if it has thinned out lately.

I had previously thought it might be Smith, but McAllister makes more sense.

YES, EVERYONE IS AWARE. WE HAVE ALL WATCHED THE EPISODES. IF SHERIFF McAllister is LEFT HANDED THEN WHY DID HE SHOOT THE GUY ON THE ROOF WITH HIS RIGHT HAND DUMMY? THESE EMIPODES STINK! I USED TO LIKE THIS SHOW, BUT ITS GOING OUT VERY BADLY. NOT A GOOD WAY FOR THE FINAL SEASON TO END!

Are you guys aware that Sheriff McAllister´s first appearance was during the second episode of the first season and he returned just now as a rj suspect? 

When Sheriff McAllister saves Patrick on the roof (Season 6 Episode 3), he helps him up with his left hand, indicating that he is left handed. When Red John is choking Kira Tinsley, he uses his left hand, indicating that he, also is left handed.

10% of people are left handed
There are 5 suspects remaining on the list

Do the maths for yourselves. Thomas McAllister is Red John :D