Let's assume Haffner is RJ, for the reasons stated in other theories. I think someone here also said that Heller said that PJ will face a dilemma when he catches RJ- what to do. My theory is that when PJ catches RJ (lets presume its Haffner), Lisbon will be taken by the "Tyger, Tyger" group and RJ will be the only one who could help, so PJ will be faced with a choice between saving his friend or getting his revenge. Also, remember when Bertram said that he wants to be there when RJ is caught? I reckon this is because RJ knows about the "Tyger, Tyger" group (which I think Bertram is a part of), and he wants to kill RJ before he reveals the secret.

“Tiger, tiger”
organization has always appeared when someone is killed. Maybe to recognize each
other, that they are doing something in behalf of the organization (killing of Kirkland)
or to ask for revenge from the other members because the killed one is part of
the organization (Partridge, Todd).

The only
link between “tiger, tiger” and RJ was made by Brett Stilles who said RJ is preparing
a party (with Kristina Frye), who was abducted by the killer of the 2 copy-cats
(everybody consider that he was RJ) who recited the tiger, tiger poem (and at
the end mentioned some “best whishing” on behalf of Kristina and also mention
the “roll tide” expression, connected also with Kristina).

If Stilles
wouldn’t mentioned RJ in connection with Kristina, there would be no real connection
between RJ and the two copy-cat killer, and the copy-cats killer would have
been only a member of “tiger, tiger” organization who came to rescue Jane, not
necessary RJ.

A
conspiracy theory could explain these discrepancies by the fact that Kristina
was kidnapped by RJ from one who has kidnapped her first.

Also, Todd
who was put on fire in CBI, never mentioned RJ, he mentioned only a big
organization. So he could be put on fire by a member of “tiger, tiger”
organization to silenced him and not by RJ, and that put Jane on a wrong track
(a red herring) in search for RJ.

The
tiger,tiger organization could be an organization that do some “justice” when
the legal system can’t.

So, I
consider RJ and “tiger, tiger” organization two different things, with no
connection.

And for
many reason mentioned already, I consider Haffner the most fitted suspect to be
RJ. His previous position in CBI could give him information about tiger, tiger
organization. That could help him to give Patrick a red herring with the tiger,
tiger poem (if he was the real killer of the two copy-cats)

First and foremost,  I
honestly have no clue who Red John is. 
There have been so many clues; however, most of them are subject to
various interpretations.  I prefer to
stay away from all of these clues because I don’t want to speculate on
something that could go multiple different ways.  Reading many of the theories on this site,
many people aren’t convinced of certain things. 
For example, is Partridge really dead? 
Do we trust the info on the psychiatrist’s recorder about Red John?  Is McAllister crossed off of the list of
suspects?  Is Red John a group of people
or just one person?

So, if we are to assume that Heller is being straight with
us about this list of 7 suspects, then that is really the only true fact that we
have.  The rest is interpretation and
speculation based on interpreted information that could have been easily
misinterpreted or purposely planted by Red John to mislead.

The one thing that has bothered me throughout the entire
show is the fact that Red John is always one step ahead of Jane and everyone
and everything for that matter.  Some of
RJ’s knowledge and actions seem almost impossible for him to know or do unless
he is some type of omnipotent being.  This
is what has troubled me the most.  So
this has led me to believe that RJ must have accomplices or that RJ is a group
of people.  However, I struggle with this
concept because the more people that know about something, the harder it is to
keep it a secret and maintain control.  Ben
Franklin said it best… “Three can keep a secret if two are dead.”

Now some new light has been shed on this Tiger, Tiger
concept.  This might help explain things
somewhat, but now I am speculating. 
Tiger, Tiger appears to be some sort of secret group within law
enforcement.  Perhaps it is a ring of
officials/politicians/cops/etc that will do bad things in the name of justice (planting
evidence and including killing others to keep their secret).  Or maybe they are just corrupt through and
through… though I don’t think so. 
Regardless, the Tiger, Tiger group could be how Red John is able to know
so much and accomplish so much.  Either
they work directly for Red John and know Red John, or it’s the opposite…  I think they have no idea who Red John is, but
Red John knows everything about them.  As
a result, perhaps Red John is able to manipulate certain information and even
manipulate certain actions from the Tiger, Tiger group.

He may even be a part of the Tiger, Tiger group.

This helps explain my dilemma that I have struggled with throughout
the entire series.  Red John is Red John
(not a group of people) and therefore, his identity is more easily concealed.  However, Red John is somehow able to
manipulate the Tiger, Tiger group into obtaining information and performing
certain actions on his behalf without them knowing it.  Because the Tiger, Tiger group does its own
illegal activities, this makes it easier for RJ to manipulate the group.  This explains how he is always one step
ahead.

Or perhaps Red John is a red herring.  A serial killer was invented by the Tiger,
Tiger group to cover up the elimination of certain people that they wanted dead
for whatever reason.  Though, I hope this
is not the case, and it does not make sense. 
If this were true, then Jane’s family would still be alive.  They were killed because Jane called Red John
out.  If Red John were a group of people,
the group would not have cared about this or taken it personal.

Why was Kirkland killed? 
What purpose did it serve?  I
presume the answer to this is simple… He knew about the Tiger, Tiger group and
therefore he knew too much and had to be eliminated.  I can’t think of any other purpose that would
have been served for them killing him.

One other thing that is bothering me.  At the end of season 5, RJ tells Jane he is
going to start killing again and with more frequency.  Assuming RJ is who killed Partridge… then why
did he specifically kill Partridge and where is this alleged increased
bodycount?

Ok folks im going to blow this case right out of the water so read and learn.

1) Red John is not Walter Mashburn, Van Pelt, Ellis Mars or any other dumb people you keep accusing. So please stop with those crazy ass theories cause they make no sense and are a waste of time and space.
2) Brett Partridge is not RedJohn. He is dead. Plotnick and Heller both confirmed it. Give it up already.
3) Micheal Kirkland is not Red John. Jason Cooper knew who RedJohn was. Dont you think that when he saw Bob Kirkland he would have recognized him or his brother as RedJohn??
4) Tom McAllister is not Red John. Red John while visiting Ms. Harker was wearing a suit and drank tea just like Patrick. We have only seen McAllister in his uniform and nothing else. Also does McAllister look like the tea drinking type? He looks like more like a guy who would drink a cold beer at the end of the day kind of guy dont you think? As far as him being scared of pidgeons goes thats a red herring people. You would react the same exact way if a bird came swooping at your head. It doesn't mean anything. Also it appears that McAllister is part of this Tyger Tyger group.
5) Gale Bertam and Reede Smith are also part of the Tyger tyger group along with McAllister and Partridge. It would be very hard for Bertram to run the CBI, secretly run this Tyger Tyger group and still have time to be RedJohn. Same can also be said for Reede Smith. It would be very hard to do you job at the FBI, take care of the dirty work in the Tyger tyger group, have time to be Red John and not slip up and get caught. So Bertram and Reede Smith are not Red John.
6) Bret Stiles is not Red John. For one thing he is to old and doesnt match the physical description of RedJohn. Second he is the leader of Visualize and very recognizable. So Sophie Miller would have known who he was and would have also known who Gale Betram was for that matter. Stiles knows who Red John is but is to scared to reveal anything. His teachings and being in Visualize made RedJohn who he is today.
7) Raymond Haffner aka "RED JOHN".  Haffner fits the physical description of Red John. He has a knowledge of wiretaps and different kind of servalliance but he was an FBI and CBI agent.  He wears a very nice suit all the time. Just like Red John did visiting Ms. Harker. He's a very charming and good looking man. Red John is known for manipulating people into doing anything he wants. A nurse accidently goes to the wrong room lookng for a "Carmen Lee". Then Haffner comes to visit Lisbon? Coincidence? I dont think so. Haffer is a member of Visualize so who knows all of their techniques. When asked if he was at the Elliston farm is 1988 he ignores the question.  He tried to get Lisbon to join his security agency and obviously has a thing for her. Red John after kidnapping her instead of killing her paints a clown face on her. He asked Cho if he thought Patrick was smarter than him like is was a game or something. Red John and Patrick's relationship is like a game.
People it's Obvious that Haffner is RedJohn. Everything fits perfectly. Those of you will say that Haffner isnt smart enough to be RedJohn. Its called acting and not drawing any suspicion to yourself. Bertam for example in front of Patrick quotes a William Blake poem. Do you really think somebody as smart as Red John would tell Patrick the Tyger tyger poem and then turn around and quote another William Blake poem right in front of Patrick and not thing Patrick would catch it?? Raymond Haffner has never done anything to make himself look suspicious. He's to smart for that.  RAY HAFFNER IS RED JOHN.  ^_^

I'm starting to think that Red John and Tyger Tyger are two different organizations altogether.  O'Laughlin was a Red John conspirator and it was assumed he killed Todd Johnson (I could be wrong but don't remember him admitting it).  But Bertram was on LaRoche's list of five as well.  I think that Johnson was an enforcer, killing mainly police officers to help protect Tyger Tyger, his "part of something bigger than Jane could imagine."  I think that Bertram killed Johnson to keep Tyger Tyger a secret.  This would also explain why, before killing Timothy Carter, O'Laughlin and Bertram hadn't put their heads together (they aren't part of the same organization).

Also, how do we know it was actually Red John that saved Patrick when the copy cats had him.  It could have been someone in CBI that was watching him (they were obviously putting resources in to keep tabs on him).

We have Kirkland dead; Partridge dead (more than likely, even CBS trailers whittled the list down after his episode, also he appeared to be in Tyger Tyger based on his last words); Bertram, Reede, and McCallister seem to be part of Tyger Tyger; and my gut is that Brett Stiles was a mentor of sorts of Red John.

This leaves Haffner.

But what are the purposes of the two groups (Tyger Tyger and Red John). Perhaps Red John was fed into more of rivalry with Tyger Tyger, perhaps Tyger Tyger stages some of their crimes and (with the help of people like Partridge) fixes the blame on others, perhaps Tyger Tyger had some purpose to kill Jane's family (to shift focus or cover something else) and blamed it on Red John (which would upset RJ and cause him to focus on both Patrick and Tyger Tyger.

Also, if PJ was given some type of post-hypnotic suggestion (by RJ or Tyger Tyger) perhaps it was to respond to the words Tyger Tyger? 

Also, perhaps Roll Tide is a Red John thing, (it was said a couple of times, and Roy Tagliaferro's associate bought a stuffed elephant for Rosalind Harker)? 

Final thought, Haffner is the only one I've noticed include the 'z' sound in pronouncing Teresa (although I couldn't find a clip of Partridge saying it and only one instance of Haffner saying it).  Most suspects say it Teresa, Haffner sounded more like Terezsa (z sound with a hint of s sound), while RJ pronounces it Tereza (with a clear z sound).

I really think people have over analysed (me included) the whole show, therefore making it more difficult to find the identity of RJ. If we go back to the basics and try to piece the story together we will get our answer. US shows have poor endings people will be dissappointed, a lot of questions will be left unanswered once the reveal happens because thats how TV shows work they come from so many angles that a lot of the things that happen become unexplainable, e.g. why didn't Harker feel the face of everyone on the list" "If _____ is RJ then who did ____ in a so called episode  even though RJ was doing ____etc etc" Think of it like Scooby Doo tv show RJ will be someone that's not too obvious but not too hidden just like the villains in Scooby Doo. I think Heller originally planned on it solely being Partridge but as the show became a hit he began exploring other avenues and now is trying to untangle it all as it was slowly turning into a big mess. It may still be partridge though etc . Also Van Pelt is linked to Ray (the footballing connection) he could be her dad/brother i dont know. Jane will go on the run after the episode "Red John."  Also the writers visit this website too, they are clever but not as analytical as many of the theories. Remember simplicity = The identity.

As many theories here said, I also hope that RJ and the "Tyger, Tyger" groups are separate things, it would be a massive anti climax if RJ wasn't a specific person and a group. I also want RJ to be against the "Tyger, Tyger". However, I have a feeling that PJ is playing a trick with the list. Firstly, he told Lisbon about it, he knows perfectly well that it would put her in danger and all the people she tells (PJ knows she will). I predict that PJ will find RJ soon enough, however, he will be faced with a choice, kill RJ or accept his help and take down the "Tyger, Tyger" group. I reckon he will take them down and kill RJ later. I also think RJ is being made into a more or less sympathetic villain by Heller, for example RJ helping PJ in season 2 (I think, when PJ was tied to the chair). Also the numerous times RJ was trying to reach in to PJ and make him his friend. I for one, am really excited about the prospect of PJ and RJ teaming up for a little, the "Tyger, Tyger" group should be no problem for the 2 of them. We can see that RJ already started to take out some of the members of the "Tyger, Tyger" group by killing Partridge. I also think that the everyone on the list bar Kirkland and RJ are members of the "Tyger, Tyger" group. Haffner is my choice for RJ, he fits the descriptions and seems clever enough to be RJ + he works privately now, unlike the majority of suspects who work for the law enforcement.