Ray Haffner = Red John

Reasons

1. In episode 13 season 4 Red is the New Black RJ literally shows his hand. When you compare (color, shape and size) the hand with remaining suspects the most likely RJ is Ray Haffner. 

2. He is visualize and his age would suspect he was young enough to be at the Visualize barn.

3. He's got something in common (not only appearance) with PJ and that is his love for Lisbon