There are a lot of red herrings (everyone whistles, everyone seems to have a phobia) and it seems like most of these guys could logically turn out to be RJ. But I think it's Haffner, for the following reasons:
- RJ has a dedicated, cult-like following. That's a Visualize type of thing. That suggests Haffner or Styles.
- RJ has "friends in law enforcement." Those types of people are only friends in that RJ has the goods on them. He knows about Tiger Tiger, and is using blackmail as leverage to use the group as he needs. Again, that suggests Haffner, the guy who is surveillance expert, and has worked in both the FBI and CBI.
- Haffner is the only one of the five who didn't ask, "Where does Jane want to meet?" Haffner already knew(not sure how, but RJ seems to know a lot), but couldn't find a way out of it....
- ... except by telling the FBI where to find Styles. SOMEONE ratted him out, and Haffner likely knew where he was. When Grace talked to Styles, the FBI didn't know where he was. They only knew AFTER Haffner was told he had to meet Jane. He knew if Styles didn't show up, he was the one Jane would focus on.
- I think the three Tiger Tiger guys are HOPING to have RJ caught and out of their hair. Bertram was probably working with Homeland Security as a ruse, and was pretending to help Kirkland. He is actually a dedicated Tiger Tiger member. Or he is not, and was actually really trying to help Kirkland get info on Tiger Tiger by infiltrating them.

If I'm wrong, then it's probably Bertram.

So, I've made some points before why Haffner is looking suspicious in his first appearance (S04E02), and in his second act he continues to do.

It's the famous Red Barn episode (S05E13), and no coïnsidence our man Haffner shows again. He smells trouble, and finds a subtile reason to talk to Lisbon: he asks if she would like to start a new business with him. Maybe he's jaleous at Jane and kind of loves Lisbon (think about what Stiles once said about the patheticly jaleous character of RJ), but most of all it's kind of an excuse. In fact he wants to hear everything about the Alison farm case from her. At the end he's dissapointed the mother and daughter aren't going down for all 3 dead bodies from 1988. Probably this is a VERY lose end of his (one he not wants to be investigated further), because he was still young and careless back then - RJ in search of an identity.

Nice scene-overlap comes in the end of the episode: the daughter had a flashback to the basement of the farm and said that it felt like someone was there, someone was watching them. Next shot Haffner walks into Lisbons office (famous 'we're still friends, right?' dialogue follows).

Going back, a little earlier in the episode Haffner is so thrown off about the case that he misspeaks about Cooper who's not on the suspect-board. Lisbon is a good detective and links Haffner to Visualize immediately. Possibly she suspects him as RJ even before Jane does.


Now, of all 7 on the list I've watched their first appearence in The Mentalist and Haffner is the only one that leaves so many direct RJ-clues (indirect clues like anagrams I do not count because I catalogue them as distractions by Heller). Except Partridge, that one also bears a suspicious air around him, but I truly believe he's murdered.  

Thus Haffner's our man ;)
 

So how many episodes are in this season then? cos if its wrapped up in 8, what else can they do?

Anyone on the IMDB Cast list could be RJ, and there's still probably some names not on the cast list for episode 8. I wouldn't rush to quickly to assume Mashburn is RJ.  I think a more likely scenario is that Jane calls on Mashburn for help. Seems more logical than him being RJ. Mashburn doesn't fit the physical descriptions of RJ (does not have notable posture or straight hair) and he was not on the list of 7 (unless Heller was lying about the list--seems unlikely).

GOing with my, gut, if the kill scene is Jane straddling RJ and killing him, I just can't picture Jane having that moment with Partridge, Bertram, or Kirkland. I could picture him having that eye to eye intense moment with Hafner. I can maybe picture it with McAllister. I really doubt RJ is Reed, but I could even picture him locking eyes in that scene.

Because it implies a real physical moment, I dont see Jane having that scene with Stiles either. No proof, just my gut.

all i ask is that when patrick and red john finally meet; red john uses the creepy high-pitched voice!

How do you people know episode 8 is the end of red john??? the title colour change doesn't necessarily mean that!!

For those of us who fancy Haffner as Red John: some extra thoughts about his first appearance (S04E02).

After Jane met his new partner with a firm handshake and a shouldertab, he went to Lisbon's house and asks her what she knows about Ray Haffner. She says that he's hard and by the book, but also that he was in the FBI before and well known for resolving high profile cases by wiretapping and surveliance. Two points where RJ scores well. Even 'by the book' could be interesting if we translate it to 'principal', which we also believe RJ to be. But keep the wiretapping in mind!

Still vague. Further on in the same episode it gets more interesting.

When Lisbon is home alone and thinking about Jane, who told her Timothy Carter wasn't Red John after all, she calls JJ LaRoche because she wants to talk to miss Carter, who is in prison.

Next scene: Van Pelt, just back on board, wants to talk to her new boss, Haffner, about money linked to the murder of a gymcoach. Although she's just doing her job, Ray isn't interested at all and claimes he has no time for this. He looks hasty and worried.

When lisbon arrives at miss Carters' cell (together with LaRoche), the lady is dead. A staged suicide with a fake letter in which she acknowledges her killed husband as Red John. Jane arrives a litte later and he can obviously see it's corrupted.

How could Red John be one step ahead? Because he wiretaps LaRoche's office. Who's good at it and was in a troubled hurry right after Lisbons made the call to LaRoche? Right, Haffner (who might know Smith well since he was FBI before).


So, it's maybe not a coïncidence that just after the fake RJ was shot by Jane, the real RJ appears on stage AND tries to work together with Jane. He felt finally safe to reach out to his old friend in person - untill Lisbon tries to dig up the whole Carter affair again. So he acted fast as light and wrote a fake letter to fortify the story that RJ is dead.