i dont know who red john is, especially to this point, no matter who red john is, a lot of people will be disappoint. 

I just watched the finale of season two again, listen to the voice of the "red john" who saved jane's life
" If theres one thing i cant tolerate, its cheap imitations copycat of my work"
"do you know who i am?"
Thats clearly Kristina's voice. Then later when she was reciting the tiger poem, the voiced changed a bit. 

I more believe that bruno heller has no idea who red john is, or he is changing his mind along with the show goes.