Not a theory just some thoughts 

1) Before he gets shot, Kirkland says to Reede "Why don't you just do it here". This implies that he knows he's gonna get shot and it has to go with how prepared Rob is. From his perspective, all he wants is for RJ to be killed, but once Rob's gonna go to jail he knows that he can't kill RJ himself. I think Kirkland knew that he was gonna get killed but its all part of his plan, as maybe his death can be used as a clue for Patrick to figure out who RJ is or to uncover the tyger tyger conspiracy.

2) I also think that RJ and the tyger tyger conspiracy are two entities and are actually enemies. Throughout the show RJ has been shown that he wants to be Patricks friend and that they can lead a "higher path" together. RJ has also shown that he does not believe what he's doing is wrong and that when he dies people will remember him positively. Maybe RJ is trying to get Patrick to help take out the tyger tyger conspiracy. As for the disappointment when we find out RJ, its possible that some of the people RJ is murdering are actually evil and part of the tyger tyger conspiracy group, so Heller might be referencing that we are going to be disappointed when we painted RJ out to be a villain when potentially he isn't. This would seem to support RJ's thoughts of not being wrong when he murders, and attempting to get Patrick to be his friend.

What do you guys think? 

The DHS building in Sacramento where Kirkland works is actually the Department of Energy building in Washington DC.  More Mentalist trickery where Kirkland is concerned.

go youtube: http://www.youtube.com/watch?v=590v4FCm6WU there is shown the last episode of season 3. Where Jane kills Timmothy Carter, because he thinks he is Red John. Stop the Video at 00:52. Then you will see a man in a red sweater. Kinda looks like Robert Kirkland. I think it's his twin brother Michael. Before this episode was shown in TV Bruno Heller (the producer of the mentalist) said that we will get "a glimpse of red johns real face" ! Well, there he is! Michael Kirkland. 

Remember that Kirkland had Jane kidnapped in a cabin, that cabin (property of Michael Kirkland) was said to be surrounded by pine trees (the earth is implied). Bob was manipulating a hammer and he didn't even use it (one can relate hammers to nails). And remember that Rosalind said that Red John smelled like pine, nails and earth. I don't think this is a casuality. I didn't think too much about Michael at first, and my suspect was Haffner, but now I don't know. 

Apart from the "Tyger, Tyger" theme, taking a closer look to the actual poem RJ recited, I couldnt overlook the ending. "...thy fearful symmetry?" So my guess is Mike Kirkland, Bob's twin brother because what more symmetrical than a twin?

For all those questioning why Bob Kirkland didn't ask Lennon about Red John.
1. It was Mike Kirkland in the hospital room with Lennon.
2. He went there simply to 'kill' a loose end FOR Red John, as he is obviously a 'RJ disciple' doing RJ's bidding. He didn't need to ask where RJ was or who he is, simply because he knows already and was there on RJ's behalf.
3. Listen carefully to the conversation between Lennon and Mike Kirkland: especially where Kirkland says 'your mind is clear'. That's hypnotism right there.
4.Trigger words all over that conversation.

Mike Kirkland is not RJ, but he sure is a friend of RJ's.

There are many questions to be answered by Bruno Heller and I feel that these questions don't do any justice to the storyline:

1. Why did Kirkland kill Jason Lennon if he was looking for Red John? 
2. Who was that person in Sheriff's uniform who killed Rebecca? 
3. Who was the person who played the role of Masked Red John in Season 2 finale episode?
4. How did Patrick Jane shortlist his suspects? By just thinking that they could be in all the crime scenes. That is just so stupid.
5. Rosalind Harker and Sophie Miller say that RJ is a middle aged man, good physique. Why doesn't Patrick Jane eliminate Brett Stiles and Reede Smith. Out of remaining 5, if these both are eliminated, that leaves us with Haffner and Mcallister. 
6. Why did Sheriff Mcallister remove his moustache? ( Not much relevance but is important)
7. What is about this "Tiger Tiger" organisation? Why was this revealed now? One more stupid plot.

I am sure that Heller will have stupid answers to these questions. I loved the show, but now it has just become like a bollywood movie.