I've been watching and reading theories here pretty much from the beginning and thought I'd finally share my thoughts. This is the first of them.

This time I suspect Robert 'Bob' Kirkland, the Homeland Security agent. Anyone who has watched the fifth season knows this guy and everyone knows he has something to do with Red John. I will analyse every option.

First let's say he's RJ himself. I personally think he'd make the best Red John of 'em all. I know he might be a bit too obvious and suspicious but maybe Bruno Heller wants to fool us with that. He has always made all the tricks so suprising and this time the most obvious could in fact be the most surprising.
  He's appearance is something I've always thought RJ woild have; His voice, height, personality etc. Also fits Rosalind Harker's description.
  Now to the scenes of the show. 
First appearance: The limo scene was suspicious and the fact that Kirkland has actually always been there makes it a good twist.
First meeting with Jane: If Kirkland is revealed to be RJ, this scene will be pure gold. The lines were brilliant!
Kirkland: *bumps into Jane* Sorry mr. Jane.
Jane: Do I know you?
Kirkland: No, but I know you. *Shakes his hand and smiles, then walks away*
And the music makes it all even more epic. This happened in the episode before the one where Lorelei tells Jane he has shaken hands with RJ.
Link: http://www.youtube.com/watch?v=L5-H9QGov4Y
Killing Jason Lennon: He asks Lennon if he recognizes him and the answer is negative. Maybe Bob manipulated Lennon to forget his face (RJ can manipulate people) or he had a face surgeon.
The list: If he is RJ then it means Lorelei is still alive. They just tricked Patrick so he wouldn't suspect that.
That's pretty much all I can dig up. If RJ then he could be Patrick's brother. It's possible that Patrick wasn't the only child.

Also it's possible that he's like Jane, trying to catch Red John. It would explain the list and that killing Lennon would eliminate the possibility of Jane getting info of RJ.

Now the third option. If Kirkland is RJ accomplice, he's not just any accomplice. He's RJ's right hand. Maybe a new one or the original. Orville Tanner. What if he didn't die? What if he went missing and had a face surgery? 


Sure some people would get disappointed if Kirkland is RJ. He's the best (imo) and the safest possibility. 

Thanks for reading! Tell me if I missed something important!

anybody else find it strange that RJ (or the person painting the 'blood'  on Lisbon at the end of 6:1) wasn't wearing gloves???  You could see their fingers.  In everything previously stated about RJ, he uses 3 gloved fingers to mark the smiley.  

Just a thought...Heller said that in the last scene of the first episode of the sixt season "There is a clue buried in that final sequence that will pay off big time
in the finale of the Red John story. A very big clue. No one will get
it from the clue as it is laid out in the episode, but it will pay off
later".
I've watched the finale scene a lot of times and couldn't notice nothing strange.
Then I thought that the clue maybe wasn't a "thing" but a "behavior".
In this context I noticed one thing strange: the way RJ painted the smile on Lisbon's face.
When he finishes painting the smile seems to caress her cheek.
Can this be the clue?
RJ is someone in love with lisbon or someone very close to her (maybe a member of her family)?
I don't know if this is important but is the only thing that seemed strange to me.