This is not a theory...but it looks like the writters of the show keep looking this site too mucho...2 of the 3 the top suspects in the site are "all ready dissmissed"....maybe Haffner is next?!
Honestly at this point I think every thing is possible...i really think they been changing red john since season 1...They didn't know if the show gonna last 5-6 season...so it dosn't make sense introduce red john in season 3 (bertram), season 4 ( Haffner) (Smith), season 5 ( Kirkland).

I think the original red john was Partridge...but now im not sure of no one...they dont follow the story...and every thing we all ready knew from the show we can not trust it at all...

smith to fat
stiles to old
bertram to tall

If we considered that "they say something true in the all serie the only suspect "alive" aproaches to be red john would be Haffner...

Sorry for the mistakes english is not my first lenguage...