Red John is Wayne Rigsby.  Ignore the Accuse button, it would not let me scroll down.

Everyone thinks that o'Laughlin was killed by Van Pelt at the end of season 3. But then he reappears in season 4 episode as van pelt reflects on him. Ask yourself, why would Bruno Heller do this? What is the purpose? The only explanation I can think of is that o'Laughlin is STILL ALIVE. I think it will be a shocker when Bruno Heller eventually reveals that it was actually o'Laughlins twin brother who was killed in season 3. I think we will be seeing more reflections and flashbacks of o'Laughlin as Heller builds up the ultimate climax of the series when he is revealed as red john.

I think that Craig O'Laughlin is Red John because he has looked in Red John's house.

I believe this FBI guy is the redjohn .several reasons, after his entry in the season 3 there was murder in the prison mystery over the rat inside CBI.He once hesitated to save Grace during a shoot out(Rigsby even talks abt it to CHO)

P.S Yet to watch S4 and S5