Tolman Bunting people:

 has the computer know how and contacts to crack the cbi network.

he likes games./puzzles, is super intelligent, and a kind of nemesis for PJ. 

slim, dark hair, 6ft ish.

I believe it is Robert Strickland of homeland security. Why because of Occam's razor.

I think Kirkland is RJ. After the last episode's ending, and his obvious need to find out everything that PJ knows about RJ, I would conclude that he is either working with or for RJ, or is RJ. Being in Homeland Security, he's not only close to PJ and the entire team, but also has a lot of connections. And the RJ smiley face from the episode the Red Barn could have been from him as a kid, or more likely, the original RJ is or was his mentor. RJ has to have someone to carry the torch when he's gone, right? And, if not, it's a well-known fact that he does have accomplices.

I still think its Bertram, now I do not seem to have followed everything as closely as all others but one of the clues is his relation to Kirkland (who, functioning as 'The homeland contact) could very well be an aid to RJ. Then there is an episode, which you probably all have seen and analyzed, where Bertram quotes a poem, in meaning similar to "tiger, tiger".