I really think Red John is Patrick Jane, maybe with a personality disorder that he can't remember what he did with his family and all the victims,also the Red John smiley face looks like him at least thats what I think, because he is a joker and very funny, seems to be amused all the time, or maybe someone related to him very close to him, but if not; for me its too obvious is someone from the inside with high rank, a cop or someone from the team. Some times Grace looks very suspicious too, her computer always have received the messages, weird!, and she seems to be depressed, mad or bipolar must of the time, Im sure something is not right with her, but anyways everyone in the team has some kind of secret, Thats my theory!