Red John is Kirkland. In the season 5 finale we learn that Red John must have been at the same carnival as Patrick Jane because otherwise he couldn't have known about his fond memory. When Lisbon asked Kirkland about his youth he said that he travelled a lot and likes to think that he grew up in America which could actually mean that he was part of a circus as well. Perhaps Kirkland has shaken hands with Patrick there as well.

Ok, so I'm the first to admit this could be completely wrong...

But is it possible that these 7 suspects are more misdirection?

After seeing the excellent finale, Sean Barlow seems to be a suspect for many reasons.

1. Sean is the uncle of the girl who Red John murdered to destroy Patrick's childhood memory.

Is it possible that Sean was actually there at this moment, and saw Patrick's reaction to the moment? With his ability to read people he may have seen that it was a meaningful moment for Patrick.

The only other person in Patrick's memory was the girls Dad, and he would be fairly unlikely, but it's quite possible Sean was off to the side watching.

2. I believe the video Patrick watched at the end of the finale was made before Kirkland broke into Patrick's and stole the information on the wall.

So how does Red John know the 7 suspects Patrick would land on before he actually had?

An idea I had is that all 7 are accomplices of Red John and may actually assist each time he murders someone. This puts them all at each murder scene, which is how Patrick came up with these suspects.

Sean could be using this as a misdirection tool and also, as Patrick first met him years before, could be arrogant in thinking Patrick would never think of him.

But acknowledging Patrick's abilities would have realized that he would come up with the his 7 closest associates. 

3. Sean knew Lisbon was in love with Patrick and used this knowledge to show off his so called psychic abilities.  This could just be his abilities at reading people, but it's possible that it's because he has been following Patrick and Lisbon closely.

Lorelei accused Patrick of being in love with Lisbon earlier on in the season, so if she knew there were feelings brewing under the surface, so would have Red John.

4. The other people in the series who have taunted Red John have ended up dead. Why hasn't Patrick?

My guess would be it's a rivalry of some kind. Sean Barlow and Patrick Jane come from the same background, both showmen with amazing mentalist talents.

Red John wants to prove he's better and smarter so instead of killing Patrick, he kills his family. Then he continually taunts him to show he's smarter. He enjoys playing with Patrick and making him suffer.

It just seems a lot more personal in the way he's tortured Patrick for years instead of just killing him. This is why it could be family related.

This fits nicely with Sean Barlow because of the past family tensions mentioned. The "business deal gone bad".

Also, Lorelei talked about how how Red John reads people immediately and is that he and Patrick are very alike.

Sean fits this description more than anybody (Apart from Bret Stiles).

It's possible the other suspects could be putting on a front, but in terms of what we know about RJ, Sean is master manipulator just like Patrick.

On a side note, the reason I don't believe it's Bret Stiles, as Lorelie talked about how it was strange they weren't lifelong friends from when they first shook hands.

Patrick and Stiles have always been fairly pleasant with each other and even helped each other out, so they could almost be loosely classified as friends (unless I've missed episodes where this is not the case).

Now, they could both be playing each other, but in all honesty they don't seem like mortal enemies.

5. After the meeting with Sean Barlow, Patrick was quite dismissive of the conversation, saying he couldn't read him. I found this odd especially since Sean was practically mocking him about being a step behind Red John.

He could have been doing this to once again throw Lisbon off and keep his cards close to the chest.

Sean also said that Red John had powers, and as Patrick mentioned, Sean's family like to pass themselves off as real psychics.

Just the fact that Sean really seemed to take a strange amount of interest in Red John for someone who was only very distantly tied to him.

6. Finally, apparently Sean Barlow will be a recurring character in the next season, which means there's a slight chance of this theory being correct!

Just some crazy ideas, but who knows right?

I was wondering , he said at the begginning of the episode, that he concluded names of people he shook hands with AFTER his wife was murdered, what about people he knew BEFORE and it actually might be someone from his childhood, or im just stupid P:

I am very angry beacuse some of here so silly.

"The cards are up on the table and they're the real cards," Heller tells
TVGuide.com. "There is no sort of double twist. There's no more messing
around. We've been through all the twists and turns of plot, and we're
now getting to the truth. Only the truth gets revealed from now on in."

So, one of them (7 suspects) is the real Red John! There isn't trick. And he also said before Patrick Jane isn't Red John!!!!! Despite of there are more than 100 theory about Patrick Jane!!!! It's a shame!!

My opinion is, Brett Partridge or Gale Bertram is Red John. If the handshaking was true and we saw it, obviusly Gale Bertram is the nemezis serial killer.

But, my first guess is since end of the season 2: Brett Partrige is Red John.

I'am fine because:

"This is the final chase," Heller says. "We will know who Red John is
and we will catch him next season. Everything that has happened over
ther past five years will come to a head, and things will change
drastically. This is the biggest finale in terms of game-changing and
setting up for the last act of the Red John saga. This is as definitive
and revolutionary as you can get."