I think it is Sheriff Thomas McAllister. He is only the Red John suspect who's age has been pulled down from his real life age. He is really 57 but in the show he is 50, it seems like they are trying to make him younger to fit to be Red John. Why didn't they change other characters ages? Why only him?
He is also the most unlikely suspect that we think he has no possible reason to be Red John. Just like in all of the episodes of The Mentalist, we only know reasons of the suspects to kill whoever has been murdered and we only find out the reason of the actual murderer when he explains it when he gets caught by Jane.
He and Ray Haffner are the only suspects out of the seven who has appeared with the word ''Red'' on the title of the episode. Also the case of the married couple in S1e2 in Napa connects to the story of married couple Timothy Carter and Sally Carter. And on the next episode of Mentalist they are going to focus on Thomas McAllister and things will happen that has no connection with Red John but I think that the things that will happen will make sense when they slowly get closer to Red John.
