First of all the biggest problem with all the fans posting here (including myself) is that we are trying to defeat scriptwriters (particulary Bruno Heller) by predicting the outcome. But at the same time we are hoping that Heller would be able to defeat us and none of the existing theories would be true. So our needs include some inner paradox, which makes hard for us to generate completely uncrushable theories.
Second, most of us are posting deductive theories and there is a lack of inductive ones. You see, deductive theories are limitless, because almost any person, even the most unbelievable one, could be introduced as RJ. For example, PJ's daughter, who is supposed to be RJ's only child victim! I can create a theory from nothing about her being RJ. I can say, that RJ is a mask and the person behind it is changing time by time. RJ who killed PJ's wife was Tim Carter, but he couldn't kill the daughter. We know he had some weakness for girls (remember the hostage victim Mrs. Carter was keeping). So he just took her to his home (replacing with his previous hostage's body), and later the child became RJ.
So, I must ask you to pay more attention to the facts and not the guesses. Here is my inductive theory made some months ago, before the current season started: http://www.whoisredjohn.com/See-a-theory-Red-John/3591
And a deductive one, also by me: http://www.whoisredjohn.com/See-a-theory-Red-John/4438
You see the difference.
By the way, now I'm still thinking about McAllister being the most probable suspect. Actually two new facts about him were revealed: smelling abilities (shampoo and oregano), hunting (there was something about Africa, where Carters met RJ, so safari is a good connector here). I would also add the game they played with PJ in S1E2. What were they doing? Shaking hands!
Other facts, shown during these last 3 episodes, are:
Trap for Lisbon (still no clear reason, just guesses)
Partridge saying "Tyger..."
Electroshocker
Using Lisbon's phone (attention, not RJ's, but Lisbon's) with busy hands
Miller's record
Thanks for attention!