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 ;)
 

If It is Brett Partridge..then why does Jane have to go on the run? I mean he is already dead, so when Jane kills him alone in the park, Jane then just needs to do some trickery to put him back in the morgue where he supposedly is..or BP's grave...

Sooo instead we have Jane 2 years later in South America on the run from authorities...in My Blue Heaven...