Well Patridge is an obvious person to accuse because of his voice and dislike for PJ and the latest episode make it possible to be kirkland I am going with Bertram. Patridge was creepy and "erked" PJ tis creepy personality and cowardness would offend Red John. Red John has to be someone who can manipulate not creep people out, That level of sophistication takes him out. Kirkland is too obvious Bruno Keller is a smart man wouldnt make it that easy. RJ is constantly ahead of the game with PJ and so it has to be someone inside the CBI. Bertram has always enjoyed Patrick as Red John does, he is fond of him even after the whole issue with Highytower. He also has the financial means and connections to be Red John. Further more in alot of the episodes he plays dumb as if Patrick is teaching him along the way, which makes him less obvious along the way. He also has the training and background to know how to kill being in law enforcement. He also was at the mall, which gave him a front row ticket to see Patrick think he killed Red John. This is something Red John would never aviod seeing first hand.
