Start reading this theory with your mind set to RED JOHN IS WALTER MASHBURN.
Red John(AKA Walter) has no female accomplices,he slays women rape them and paint with their blood.
Throughout the past 5 seasons we knew RJ has many male accomplices almost everywhere CBI,FBI,DA and visualize ,he never kept a woman alive except for three and only three Rosalind Harker , Lorelei, Kristina Frey.
He never kept a woman alive for as long as Lorelei or even still alive (Kristina and Rosalind ).
Pay attention to what Walter is saying at 0:34 in this video:
http://www.youtube.com/watch?v=oPVASLzF1Z8
"My second..nah my third wife was into this .....) he was referring to Kristina Frye as she is the third female that RJ kept alive.
Now lets see what we can match from the clues in last night's episode:
He has a fear of Acrophobia (fear of hights) : Unconfirmed.
He is middle age : Walter is.
He has no living family but many friends he relies on : Walter is .
He is a a excellent whistler : Unconfirmed.
He is a damage and narcissistic individual : Jane couldn't read him and yes hes damaged.
He doesn't deal with conflict and adversity easily : Unconfirmed.
He speaks rather convincingly when lying outright Walter is.
And if you watch Walter scenes he wears red shirts , red Ferrari , red boat.
I am convinced that Walter is RJ but i don't think the Walter character had time in the show to develop for the audience to enjoy and be satisfied when RJ is revealed to be him.
