Taking the names of  "Roy Tagliaferro + Red John", we can unscramble the letters out to compose "lady or tiger" (I still don't know what to do with the remaining "j-a-f-n-r-e-o-r-o-h-" letters, but I'm working on that), which leads us to a very famous short story written by Frank R. Stockton - "The lady or the tiger?". If you read this short story you'll see it fits fine to the show's events line, but most importantly, I think we've been checking that William Blake's poem on the wrong way: it may be just a clue to give us the word "tiger", which means other clues are yet to be released.

Anyway, back to the short story, there's a semi-barbaric king, whose sense of justice was quite peculiar (you have to read the story to understand). But just a crazy idea: what if Red John is some sort of a king (a public authority)? Even further: what if "he is ma" stands for "he is mayor..."? We'd better check that.

I have many theories on who red john may be, but what I want to know is WHERE THE HELL ARE THE NEW EPISODES. two weeks ago the mentalist didn't air because of the survivor finale and last week they show a rerun? this is getting ridiculous. 100+ episodes and we still have no idea who red john is. I am starting to loose interest in this show very fast.

What do you think about Handshake induction it's a hypnosis technique.Just search on the internet,is very interesting. Maybe RJ hypnotized PJ when they shook hands and RJ is not on the PJ list,because he don't remember when they shook hands or is a member of the CBI that use hypnosis to misguide Jane(1.is possible to shook hands more that once and 2. is possible to use hypnosis on jane when they are working on a case).
 "If you don't want your subject to know what you are doing, you simply distract their attention, usually by some appropriate remark, and casually terminate. Sometimes they remark, "What did you say? I got absentminded there for a moment and wasn't paying attention to anything." This is slightly distressing to the subjects and indicative of the fact that their attention was so focused and fixated on the peculiar hand stimuli that they were momentarily entranced so they did not hear what was said."it's on wiki.
I think the "shooke hand" it's more that a simple shooke hand ori my theory is to complicated.

This isn't really an outright accusation, but has someone thought on the basis that Red John, is a woman, one who we have met only once before, just on a simple, usual case. One who Jane has met only once before.

One person so smart that she managed to fool everyone into thinking that they were a male? It would be the perfect disguise.

For all of the tape recordings, Red John could use an accomplice's voice, or if he's as talented as Jane(which he clearly is)could hypnotise people into recording them for him.

When Red John was accused of rape-ing Lorelei's Sister, do you think that he/she would have been smart enough to not actually rape her? I mean, they could do a DNA analysis on the sperm and find out his identity!

OR

It could be a man, posing as a woman posing as a man...

Honestly, I have no idea. But y'know, everything is possible...Right?

AND doesn't Red Johns symbol seem very similar to the Death Eater's symbol in Harry Potter?

Physically, they look different, but both are described similarly:

Death Eater Symbol: "Just picture coming home and finding the Dark Mark hovering over your house, and knowing what you’re about to find inside."

Red John's mark is described as very similar(except for the fact that it doesn't hover... "You see the mark first, and then you know what's happened."

I'm sorry, I couldn't resist.

So, overall:

. Red John could be anyone
. We have no more of an idea of who he is than the CBI do(unless it's one of them O.o)
. Red John likes Harry Potter? 
. Nobody has any idea who Red John is. In fact the only thing we have is "You've shaken hands with him before"

Aha! Now, who else is going to go back, watch all the episodes from Season 1 and list all of the people Jane has shaken hands with ever.

Just me then ... Ah well. 

I think Red John is someone we haven't met yet in the show. Someone Jane has met but we haven't seen it. Someone that is a part of a group of people that are in the show. I think that Partridge is too obvious to be Red John. I think he is connected though. Someone that Jane has forgotten about... Just remember we really haven't seen all of Jane's handshakes and I really doubt he remembers all of them. 

Dean Harken looks interesting as Red John. A meticulous and highly intelligent man with a god complex and a job that puts him in a great "push-button place" of power with incredibly deadly pathogens under his control. He appears in the episode Code Red. the name Dean means "law" among other things. Harken means "listen", and the surname is of Irish origin. Dean Harken has red hair and is most obviously irish. Roy is another name used by Red John and is also of Irish origin. He Is just under 6'0''. Moreover, Dean Harken is on Jane's list of suspects and if you watch closely his eyes seem to focus on the name before he gives a contemplative expression in the episode "Red Cherry". Any takers...?

It's definitely Kirkland. They shook hands, and he creepily said that he knew Patrick even though Patrick didn't know him. Plus, he just gives off a creepy vibe. Every time he says anything it's got creepy connotations. If it's not him, though, I think it might be Brett Partridge because his voice is identical to Red John's. Only problem is, they haven't actually shaken hands. Maybe it was just a metaphor for them meeting, but I feel like it would probably be literally shaking hands.