Much like others on this site, I tend to believe that Brett Partridge is not dead. But in fact he might actually be. We;re going to know for sure the next episode. The proofs will be Brett's dead body and another dead suspect or at least one of them.
   My attention is now focused on Bob Kirkland. There are a lot of reasons. Firstly he is an odd guy. Secondly he is interested in Jane's suspects map, so much interested that he gets a copy for him, not without giving Jane a hunch when the latter realises his space was invaded when the match piece at its place. Thirdly, at the hospital he asks Jason Lennon: "Do you recognize me? Have you seen me before?". This means either that if he is Red John, he doesn't show his face to all of his apprentices or that he's had surgery. The not matching fact about Kirkland is that he has not shaken the hands with Jane, in the past as Lorelei said.
    My other suspect is Ray Haffner, given that he is a member of Visualise and that as he refuses to answer Lisbon, he might have been at the farm when the crimes were committed. If he is the same age as the actor portraying him(Reed Diamond) is, he might've been taken as some kid since he was about 21 at the time. The not matching fact is that he is exactly 6' tall, and according to Rosalind Harker's description RJ is "just under 6' tall". But considering that Harker is blind we may as well pretend she was not really right about RJ's height.
    Finally I can tell that Lisbon is still alive because the smiley face on her face marks Partridge's death, not hers. She was just unconscious as RJ might've used drugs to get her in this state.
    Another thing I'm thinking of is that the suspects may have some connections with RJ, or even between each other.