First of all , i am perfectly aware that Mashburn isn't on the list. But the fact that he was casted as "red john" on imdb.com but afterwards removed , has to mean something (tho knowing Bruno Heller it's everything but the truth lol) .. maybe just another trick.  BUT, i still think that imdb.com posted who really is RJ but BH afterwards asked for it to be removed, because they already filmed 8th episode and it was just a normal update on imdb.  
 NOW, why would possibly Walter Mashburn be red john?(I posted this theory 6-7 months ago)
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1. Since every RJ accomplice said to Patrick Jane that they are alike, they have that same charisma and a way of carrying themselfs,he is not sneaky and the kind of a creepy guy who hides in his basement. He is a good manipulator , so why would you believe anything that Rosalind Harker said? She could be  :   a) lying ( and patrick jane couldn't detect it because he always looks at people's eyes to find out whether they're lying) 
 b) it maybe true ( because Walter Mashburn fits the description, so there's that.)
(And also, i know you guys loved his character on the show ( Waler Mashburn ) which means that he has that natural way of manipulating )

2.The mentalist is not just about Patrick Jane, but also about Red John , because he is "the mentalist" too, they are perfectly alike , they are the same. So it makes perfect sense that they would get along when they meet ( not like Brett Partridge whom Patrick Jane can't stand)

3. The fact that in 6 seasons, Walter was the only one who could seduce Lisbon to sleep with him, which : a) proves that PJ and RJ have the same taste and interests.     
b) Imagine the scenario where Lisbon has to admit to PJ that she slept with the person who killed his family. I mean, it writes itself ! lol

4. Alright , this is a big one. 
Walter Mashburn while having lunch with PJ and Lisbon said that his 3. wife was all into this mystical psychic stuff.  HIS THIRD WIFE WAS CHRISTINA FRYE. 
a) She knew and was sure 100% that his PJ's daughter never woke up when RJ killed her. 
b) When RJ kidnapped her, he didn't kill her because he liked her, she was his wife . He just hypnotized her.
( PJ likes lisbon , and so does RJ. Same goes for christina , PJ dated her for a while, THIS PROVES THAT THEY ARE 100% ALIKE.)
c) final episode of 2nd. season : last thing that RJ said to PJ when he was trapped : " christina would want me to send her love , she's very fond of you despite your differences" ( like he knows christina very well and their differences.)

5. Red John didn't know patrick when he killed his family . But now when he does, he doesn't want to hurt him anymore. In his own way, he loves patrick, he wants to be his friend. 
That's why the only two people over 6 seasons that RJ spared were lisbon and christina. ( 2 women that Patrick obviously liked )

I have ALOT more to share with you.

This is the 1000th theory that accuses Brett Partridge of being Red John.

I'm posting again some good but lost popular theories
 
http://www.whoisredjohn.com/See-a-theory-Red-John/11340

http://www.whoisredjohn.com/See-a-theory-Red-John/8587

http://www.whoisredjohn.com/See-a-theory-Red-John/10232

http://www.whoisredjohn.com/See-a-theory-Red-John/9156

http://www.whoisredjohn.com/See-a-theory-Red-John/9215

I have decided to make a theory using clues purely outside the show(from interviews).

Clue 1: Red John is on the list (Source: TvGuide)

Clue 2: Red John has been there from the beginning of the show (Source: Bruno Heller)

Clue 3: We see a glimpse of the real Red John in the Season 3 Finale. (Source: Bruno Heller)

Clue 4:Red John likes cold. (Source: Bruno Heller)

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1. There are 7  people on the list.

2. Then we're down to Partridge, Kirkland and McAllister (Red Dawn could be interpreted as the beginning)

3. In Season 3 Finale, Nighttrain probably caught the most observant spot in the history of the show.

Brett Partridge can be seen walking his dog. It is a glimpse. The images are in the comments of the link below. I don't think Bruno Heller would make it obvious, so I expect a lot of people to say "Haha, that's not him." He's got a watch on his left wrist, but that's not much...

http://www.whoisredjohn.com/See-a-theory-Red-John/11555#disqus_thread


4. Ok, to confirm Partridge is Red John, we need evidence he likes the cold. Isn't it interesting then, that they put him in the middle of a desert in the season premiere? A desert with many, many flies? Insects thrive in warm environments. And ...Jay Roth has "Acaraphobia"...or "Acrophobia". Well acaraphobia is a fear of insects that bite.  Using subtitles won't work. It still says "acrophobia" but, I'd expect Bruno Heller to pull a trick like this. Phonetically they are exactly the same word.