Agent Ray Haffner. Watch episode 'The Red Barn'.

Lorelei said Red John and Patrick had shaken hands, also has the fact that the voice of Red John, I was thinking, many say it is Brett Partridge, however, I have another theory, could it be the Dr.Wagner? One who appears in the pilot imitating a crime of Red John? Think about it, he is a therapist, it is not difficult to manipulate people like Red John does, and also the fact that he has imitated a crime and not Red John was dead, and that Red John himself "not tolerate copies cheap ", following this direction, Dr. Wagner was to be killed for a crime copy of Red John, but not this, then, is that the killer is in our face since episode 1? Sorry for the bad english, I'm brazilian

Dear reader,

please consider that this post won't get you closer to finding Red John tough it may actually provide you some key insights which might help to avoid looking out for the wrong people. 

When trying to figure out who Red John actually is you need to think OUTSIDE of the box in which the producers are trying so hard to keep you in.

They use red herrings to mislead you all the time. It may be assumed that Bruno is smart enough not to set key leads too obvious. So stop changing your whole opinion when new - actually too obvious elements - are shown (like as Kirkland saying "No, but i know you" and so on).

In order to figure out who Red John is you need lots of time to analyze the whole timeline of the story. So far we do not have such a concrete information about John that we could tell who he is. Most people are just up to do normal guesswork - and mostly (when not always) there have been many comments which countered the theories with justified arguments.

It's not that easy to find him. I guess that we have either to wait until we get serious leads (which might be at the end of the current season) or analyze really everything we now professionally. 

It's possible that dr. Linus Wagner is RJ, and who
has got caught on purpose (a hoax, then) as part of his plan to exact
revenge on Jane and make it like him, then acts through Partidge (which
in fact admires the work of Wagner in the pilot) and Carter and his
disciples, but sometimes released from prison (he has an alibi, maybe
he's replaced by a camouflaged disciple, for example with a fake beard?; in CSI Miami there's a similar plot in an episode)
and, thanks to powerful friends, corrupt guards and Stiles's help
(Homeland Security investigate on these facts and these dangerous
friendships), maybe in prison has a better deal and does what he wants.
Then escapes to the last battle, something similar to The Following.
He can manipule people from his cell, too (he write many letters and has permission to write articles on web).
He shake hands in pilot with Patrick, and could have meet Jane, previous, in the mental asylum or maybe in circus.
He could be also the therapist of Miranda.
He can create the RJ's cult as transform Jane in his disciple, as a "surprise", a "gift" for him, in his sick mind.
He know well Tijuana, he worked in Africa, like said Timothy Carter, and kills for a "higher path" )(save the african children, with the clinic's money).

Dr. Wagner said:
I can tell you're in real pain. Why not tell the truth?
And, like RJ (as said Jane in 5x05), he thinks that is better tormented a man all the life, than kill him directly.

Its Dr. Wagner in the first episode!!! Even if he was arrested by Jane, it is possible that it was a kind of "testing" Jane. It would be very logic, if red john appears in the first episode (Title episode : "Red John"!!!!!) to give the whole serie an implicite character of constructive unity. Who else would rape and kill a women to hide a crime behind Red John, if not somebody seriously mad!!
PS: Jane and Red John shook hands: There is one scene in this episode where the camera focuses particularly on the hand shaking of Jane and Dr. Wagner.

Guys please forget this Kirkland thing. Kirkalnd and Jane shook hads after Lorelei arrested.

Do you think Kirland is going in the federal prison and he says:

Kirland: "Imagine that honey, I shook hands with Jane.."
Lorelei: "OMG WFT ??? :P ::P"

Seriously?

I think Kirkland investigating in the RJ case and he thinks Jane or any CBI  team is Red John. The reason that the Homeland Security is interest abot CBI  is very simply. There is  lot of moles in the CBI  (Red John, Volker, Visualize). There is a state department, it's a national security risk.

Bob Kirkland is Red Jonh....
wh0 :
1. He say 'Thank You' to FBI's boss , when she called the former CBI boss, Virgil. (season 5 episode 5)
2. Homeland Security (season 5 episode 7)

Why :
1. Lorelei Martins had spoken accidently to Jane that Red John 'had shake his hand' with Patrick Jane.
And Bob Kirkland (Red John, assumed) had 'Shake his hand' with Jane, and Jane didn't know him (Season 5 episode 7)
2. Bob's sound is very similar with Red John's
3. Bob lead investigation searching lorelei Martins whe she break the federal prison with Jane (season 5 episode8) and after that, Bob is just dissapear.