It has become disappointingly obvious by now that Red John is the "dead" McAllister.McAllister, whom I'd rather name with an extended monologue:"BRUNO HELLER: I can't really use Partridge anymore. They figured him out too quickly in season 2. Besides, I need someone who looks more powerful. I ran around for three more seasons and pretended that I knew where to go with it, but I finally need to choose a new Red John now. Hmm. Well, I guess I'll just pick any random season 1 male character. Eeny-meeny... Oh, yeah, this guy looks good. Who's that? A hick sheriff, just like on 'Profiler'! Ha! They'll never guess THAT!"
So why that non-choice of McAllister? Several reasons, but one of them is because Bruno Heller has been, to put it gently, following the older series "Profiler" for a few years, and Profiler's Jack was eventually "revealed" as a redneck sheriff as well. (Incidentally, Jack was supposed to be someone completely different when the show started... just as was the case with "The Mentalist". The difference was that Profiler's creator left and took his idea with him, while Bruno Heller stayed with The Mentalist - he just didn't decide whom to pick sooner).
Shame. Bertram would have been perfect, and such a satisfying choice for Red John. 
Instead, we get an idiot drawling hick who LITERALLY couldn't win a game of rock-paper-scissors. Now watch this space to hear a convoluted "explanation" next week, about how it was only Red John's ingenious act, how he only pretended to lose to Jane, how he can imitate voices so well that the hick accent was all too easy for him to do for years, every day... (which will probably also be the dumb and convoluted "explanation" for Red John's different phone voice). Yecch.
(ONCE I'd like to see a show in which the twist is that there is NO twist. Bertram looks guilty now, so most viewers expect a final twist in the next episode... and there WILL be a stupid twist, with McAllister being named Red John next week. But what a nice idea it would be for a change to reveal that... there IS no twist, that Bertram IS Red John.
Every Z-grade movie and series wants to have a pointless twist now. Having NO final twist would at least be original! Especially when the twist is as lame as a random redneck sheriff.)