RJ's blind EX girlfriend said in season 4 that rj is not taller than 6 feet 
So, it just can be 3 out of the seven suspects:
-Brett Partridge
-Bret Stiles
-Gale Bertram (not sure)
AND: The list of the seven suspects is not a fake. Bruno Heller himself said so.

Sorry for my bad english....:c

Apart from Who is RJ there's other questions to consider.

How will he be revealed?
Will Jane shoot him or will RJ go to prison (or maybe go free for some reason)?
What will happen to RJ's accomplices?
What were his reasons for killing - apart from being crazy?
How will Jane go on with his life?

Sheriff Thomas McAllister.
He is not my main suspect, but let me show you something interesting.

Nobody
would have bet a penny on Sheriff Thomas McAllister before he was shown
in the list of the seven suspects. McAllister and Reede Smith are two
who we didn't expect to find there, but they are. And it's right, in my
opinion: the presence of some unfamiliar faces makes the list more
realistic. But, who knows, maybe Red John is one of these two and
Sheriff McAllister shouldn't be understimated. Never say never (well,
actually I say definitely "never" to Reede Smith, but nevermind).

He would be a bit oldish, but not as Stiles.
Let's see what could make him suspect!


First, the way in which he was mentioned: he is the only one who was
mentioned along with his profession. Actually I think, but I'm not sure,
that the habit is to
always specifying the rank of "sheriff" when
one of them were named. So nothing strange. Moreover, it would be stupid
if he has this form of respect for himself only and so he suggests his
identity to Patrick. And then, even Patrick wrote the name that way in
his suspects stickers.


Let's pass to more concrete details: we saw him only in episode 1x02
and since his first words he arouses some suspicion. talking about the
victim, he says she has a
familiar face, and then, turning to Patrick, he adds with a slight smile that people sure look different when they're dead.

he would seem a bit skeptical about Patrick's clairvoyant skill.
Patrick, as usual, denies he's got "powers", then he challenges
McAllister at rock, paper, scissors, always defeating him. Of course
that could be an act by McAllister and maybe it was he who wanted to
lose.
But it's just an assumption, there is nothing that could prove it.


At some point they catch a certain Hector, the victim's boyfriend, who
was wearing a hooded sweatshirt similar to that one worn by Red John in
some circumstances and by dr. Wagner when he killed the victims in the
first episode. during his interrogation, when they asked him how he knew
the victim,, Hector locked eyes with McAllister, then he evaded the
question, peppering the conversation with some claims which recalled
those of John's followers. Then, they asked him what happened the night
of the murder: again, he locked eyes with McAllister, then he gave his
version.

At the end of the episode for a few minutes McAllister
was suspected to be the killer, because he popped up in front of Van
Pelt and he persisted to not leave her alone. He told her he wanted to
protect her because there was a murderer who killed women with red hair.
And we know that's true, but only we should know it, he shouldn't.
Because it was Patrick's theory, not McAllister's.
It turned out
that the murderers were two chefs, husband and wife. They had a great
harmony, like Sally and Timothy Carter. Could they be all McAllister's
followers? And he, bumping into Van Pelt, was trying to make a diversion
to leave the field to the chefs? Who knows! Again, assumptions.

Lastly, There is a curious detail:

in episode 3x04 Van Pelt goes to lunch with O'Laughlin by helicopter.
The circumstance comes up again and Van Pelt asks him where would they
go to lunch: Craig says "Napa".
McAllister is the sheriff in the County of Napa.


That's all! There is something. Compared with the other suspects it's
not much, but McAllister is an option we shouldn't rule out... Just look
at how he plays the role of Percy in "Nikita"!