Robert kirkland is not RJ, I think he is somehow connected to lorelei/her sister thats why he appears when lorelei dies, he kills lennon for personal vengeance and he is out looking for RJ, this is why when he meets jane he says "no but I know you" because he knows about janes commitment to get RJ

Well this first one is more of a joke than a serious theory but I thought it might be fun to point out. The whole Lisbon's boss position kind of remind me of the Defense against the Dark Arts teaching position at Hogwarts in Harry Potter series. If you remember, since Dumbledore denied Voldemort the job, no one could hold on to that position more than a year. Now I noticed that each person in that position has somehow left:
1. Virgil Minelli resigned/quit
2. Hightower was suspended/chased out
3. Laroche went back to PSU
4. Wainwright was murdered
5. And I can't remember who holds that position right now (embarrassingly!)

Wouldn't it be funny that RJ was after the job but was denied? :-)

I kid of course!

On a more serious note, two things still bothers me about RJ:
1. I am not convinced how Tim Carter knew to be in the mall if Bertram is not a friend of RJ. Some say Van Pelt told O'Laughlin but all she told him was he was a suspect and asked him to go with her to Hightower. The mall thing, I am not sure who exactly knew about. But if it was only the team, then Bertram is linked to RJ considering the phone call he made and of course the Blake poem thingy.

2. All the built-up the show has produced about how intelligent RJ is so that only PJ is smart enough to catch him and how PJ and RJ have similar manners direct us to believe RJ is as smart if not smarter than as PJ. And the only person we saw in the show as smart as PJ is... no one but PJ. Well, maybe Stiles but he doesn't fit the physical attributes and we know RJ was a member of Visualize in the farm so he is younger than Stiles. So the choices are: either one of the characters who is the real RJ is playing dumb now to throw us off track or PJ is RJ. I would appreciate a Fight Club scenario and considering that RJ serial killing has stopped after PJ's family, it might seem plausible. Also, maybe RJ has a decoy at any given time hence changes in the voice of the masked man reciting Tyger poem compared to the limo voice. So the masked man could be Tim Carter and then some other decoy might have fooled Lorelei, and the voice in limo is obviously a tone change of PJ (or maybe this was a game Heller played to throw the geeks with good hearing off track!). So given above facts, we can justify PJ being RJ. And I love that ending. BUT I have a feeling that will not be the case. If the case is someone playing dumb, well I really would have loved it if Wainwright was the one and he faked his death. He was charming and smart enough to satisfy me of being RJ (and it'd go full circle with my first Voldemort theory). Maybe he was too young but I like him for it not someone like Kirkland, Bertram, or even Mashburn. I'd rather Stiles and even Frye over them since they have a bit of charisma at least. And that is what PJ has mostly, charm and charisma. So RJ should be like that as well to be interesting, not "a sad lonely man"!

I'm gonna stop blabbering now!

While its obvious that Kirkland is somehow tied to Red John, I think that the fact that he used a green poison to kill Lennon proves that he is actually RJ himself. Remember when RJ poisoned Rebecca? Same stuff. Green poison that killed her in a matter of seconds. My money was on Mashburn until I saw Kirkland shake hands with Jane and say "No but I know you." And I've been flip floppy on which of them it is but now I'm sure it is Kirkland. If he had shot Lennon or killed him in ANY other way I wouldn't think he is RJ.

Red John, has something that the US government fears. Just like Moriarty having the "key code" in Sherlock. He has progressed from a serial killer into a full-fledged consulting criminal. The government has to play by his rules, which probably includes killing his followers if every they get caught, and prevent Jane from getting closer to him. So basically he is pulling all the strings. Red John is a sociopath who is easily gets bored, and Jane seems to be a perfect distraction.
Robert Kirkland is NOT Red John, or his follower. He seems to tracking Red John for many years, but can't get a hold of him.
Red John is definitely part of a humongous machine.
"That is not danger," said he [Moriarty]. "It is inevitable destruction.  You stand in the way not merely of an individual, but of a mighty organisation, the full extent of which you, with all your cleverness, have been unable to realise.  You must stand clear, Mr. Holmes, or be trodden underfoot."
And Patrick Jane will soon know what he is up against.

ALEX JANE

- nobody knew what happened to him
- he knows jane more than anyone ele
- he's upset when jane backed out on one of their clients

If Im not mistaken the circumstances around loreleis father are still unexplained aren't they?

Could Kirkland be loreleis father? Not sure of his age of anything

Considering the developments of season 5, I am thinking that Red John is either:

1) Ray Haffner (his connection to visualize) 
2) Robert Kirkland (his conversation with Jason Lennon before killing him, conversation in the limo when Jame got hired by CBI)

Both of them fit the criteria:

1) Shook hands with Patrick Jane
2) Have easy access to people of influence 
3) Approximate age

Looking forward to seeing how this develops.