I apologize for my English but I'm French.

And if Red John was a woman?Erica Flynn (Morena Baccarin) has all the features: brown hair,  age, she is a sociopath. Moreover, we see manipulative, getting everything she wanted, especially among men. For example, we see an episode that CBI Ron offered him tea with a knowing smile.

Finally, if lorelei was not afraid to measure red as red can be john john is not monstrous but physically fine.

Patrick  succumbed to her charme. last words exchanged between pj and erica are "we'll meet again soon."

A theory that surprised everyone but with a big problem. She has appeared very late in the series and starred in Homeland

I suspect that Robert Kirkland is red john because when he bumps in pj and patrick asks if he knows Kirkland he replies "no but I know you" he also shakes hands with patrick and at the end of the episode where we see patrick Jane's first case when the woman in the limo ( don't know her name) says that patrick used to be in an insane asylum she looks in to the front of the car and says it's done there sits Kirkland and he says "good"

From the last episode I think RJ is Kirkland cause he's on the inside and his soft baby voice kind of matches RJ's from the episode where he quotes Tiger Tiger and he touch him before he walked away

the real red john is ellis mars. he is a psychic, so he can hipnotize people to do what he wants. and also he is someone almost no one would consider to be rj, in fact, his appearance is only in one episode, and if you see jared Renfrews writing on the wall, you can organize the words as:

he is ma
ehis mars

the double L¨s were badly writen and the look like H.