I read a theory that I disagreed with, yet upon doing so a possible clue was revealed regarding Ray Haffner as Red John:
http://www.whoisredjohn.com/See-a-theory-Red-John/7536


Food for thought:

In my opinion, the character of Red John is too smart to make a move like the one made in the argument above. I suspect Ray Haffner is the last "RED Herring" in the series, before the real Red John is revealed.

It is plausible that the Real Red John set this whole situation up, to make Ray look like Red John. I suspect Ray did have something to do with the death of the private eye, however he is not Red John. A tattoo with three marks? This clue was too easy, almost as if it was fed to us to accept.

I suspect, the real puppeteer behind the scenes, is orchestrating the down fall of the Desert Rose list of suspects. Ask yourself, why would the real Red John share a list of 7 names that his identity was on, only to implicate himself. He has been in control of himself and countless others for a very long time, while evading capture ...only to be found on a final list of 7?

Then again, Loreleis intervention changed things - so it is possible, although I don't think so. Red John is a ghost of a character, and my concern of course is with the show ramping down with the final season and the reveal around the corner - I feel the real Red John's identity will be found out, but he will simply elude capture leaving the last part of Season 6 focusing the loop on the Tyger Club and Visualize.