Im sure the producers of this show do not yet know who RJ is! Think about it.. To make sure its does not leak out who RJ is they made a decision to decide who RJ is when the series ends.

The producers will sit around a round table when the mentalist is going to be axed and decide who is RJ.

Pure genious to keep the internet massive guessing :)

People are connecting Red John with Visualize and Ray Haffner, but Ray is now too obvious, he may work for RJ, but its not him. 

We are only assuming that RJ is related to Visualize, because he was in the red barn when those two guys were killed. That does not mean he was a member. He might not be a supporter, but wants to bring them down, so he kills those two guys and then paints his smiley face outside. I get the feeling RJ does not like Bret Stiles, much like Patrick Jane does not. We have been told in different shows that Jane and RJ are a lot a like, such as Lorelei Martins says that she is surprised they are not friends since they shook hands. 

We have met RJ for sure, but the writers are not going to make it look obvious just yet. I kind of hope it is Patrick Jane, because that would be awesome writing and very deranged. 

I believe it is Jason Cooper because it is a unpredictable person. He also called stiles out of the country and made things suspicious.

Ive Heard alot of interesting theories but this is what I believe

It is not
Patrick Jane
Van Pelt
Rigsby
Ray Haffner (too obvious after red barn)

However I also believe that season five wont get us anywhere closer to finding red john, The name isnt on the list the options are too open and he has confessed to missing some people and it has to be after his wife died.

All I hope is that this doesnt end like lost and Patrick Jane is actually delusional and this never happened. So Heller if you read this do not end it like that, I will be extremely pissed off. 

To my knowledge no one has pointed this out before.
Bruno Heller is the creator/parent of Red John.
Your not trying to catch Red John. Your trying to catch Bruno Heller.

In the last show "The Red Barn"

The
show starts out in Elliston, Ca. "Ellis" ton like Ellis in Ellis Mars.
There is no real town in California called "Elliston"

Heller likes playing with names like Pa "trick" Jane. He also did it with several other names.

This is another part of a bigger whole who is Red John:

http://mentalistlist.livejournal.com/152801.html

Just a side note...did Jane kill the man that killed his wife and child? Was Red John in the room with Timothy Carter when he killed them.....ala Volker?...

i don't really have an specific idea who Red John may be because i think the show is purposely trying to mislead us into thinking that certain people who have popped up are red john
clearly they are not going to make it as obvious as someone who the viewer may suspect although they could make it so obvious that we actually just ignore them to being red john
i think whoever red john is, when Patrick has met them they seem the least likely to be a killer
Red john isn't going to act suspicious around Patrick because he wouldn't want to get caught so he can carry on with his game.
it's annoying as my theories change all the time
i thought that maybe it's Patrick himself but i don't think they would make the 'hero' the killer.
i feel like Van pelt may be connected as we never really get to know her that well and she does seem like shes hiding something.