Last night, they replayed "Red Letter" which was the second episode that Kristina Frye appeared in.  It was also the episode which directly preceded the Season 2 finale and the introduction of 'Tyger, Tyger'.  I've long thought that Kristina Frye will be found to play a role in Red John...perhaps RJ's wife, maybe she's the young girl who Jane conned while in the carnival, maybe she's related to someone he conned when he was a professional psychic years later, etc.

In an earlier theory, I listed a lot of reasons why Fry could be involved...but a new one jumped out during Red Letter.  The CBI was investigating the murder of a wealthy, high-ranking California activist campaigning against human-trafficking.  Kristina Frye was called onto the case before the CBI.   During the investigation, a huge mystery centered around the victim's illegitimate daughter...Carmen.

When the Dr. entered Lisbon's room last week and asked if she was Mrs. Carmen Lee...Jane stopped and obviously pondered something when he heard the name.  Could he be thinking back to this case, and making a connection to Kristina?  To the Sheriff, who bore a striking resemblance (looks, voice, and mannerisms) to McAllister?  To the victim's associates who were obviously well connected within the state?

Kristina Frye first appeared in Season 1, so she's been part of the story since it's inception.

The most obvious suspect is Bob Kirkland. In fact, I think it's so obvious that many of us have gone in a different direction thinking that Heller would never make it that obvious. Then there's the hospital scene. If Kirkland is looking for RJ himself, then why not question him about RJ before killing him? I think that scene is meant to throw us off, while at the same time building the suspense around Kirkland. If he turns out to be RJ, it will be explained why Lennon didn't recognize him, which  could be for a number of reasons. Kirkland could merely be working for RJ, but he has only interacted (on screen anyways) with Bertram, and he seemed to be the higher power in that scene.

Kirkland looks, acts, and sounds like he could be RJ, more than any other of the suspects. Haffner was served up to us last episode, but if you watch his past appearances, he has been outsmarted by PJ, and talked down to by Bertram. In fact, before this season, Haffner had done nothing to make you wonder what he was up to, other than his involvement with Visualize.
Then there is the Kirkland handshake scene. The only one of the seven suspects to have their initial handshake showcased dramatically on screen, complete with ominous music. Finally, Kirkland is one of only two suspects not to have appeared yet this season, which sets him aside for something. We'll see.