In the promo for 6x02 episode, you can see Sophie Miller's (Patrick's psychiatrist) face in the picture on the fridge. Above that picture is note from Red John. So, Red John probably found out Patrick's happy memory from Sophie Miller.
We know that Alexa Shultz appeared in "Red Dawn" episode where she asked Virgil Minelli to keep him in loop about Red John's case, emphasising that Patrick Jane is someone who spent a year in an insanse asylum. She is later seen with Robert Kirkland inside the limosine who thanks her for the service.
I don't really think that Kirkland is Red John: he's capable of gain information to everyone but more probably is just a good accomplice of RJ (In september 2011 Heller said that we already saw RJ in previous episods and the first appearance of Kirkland is in red dawn (2012))
so, who is Red John? I think Bret Stiles.

Sorry for my english.