Not accusing anyone here, just wanted to point out something interesting -

In Season 1, when the wrongly convicted prisoner that has info on Red John is murdered written on the wall is "He is Mar" or perhaps "He is Man"

Most assume that this clue has something to do with Red John but I couldn't help but notice that after the Red John saga supposedly concludes after episode 8 the rest of the episode titles are based off the color blue instead of red. "He is Mar" or "He is Sea" = "He is Blue" perhaps signifying that whoever murdered the ex-con wasn't Red John but this new blue-themed threat?

Obviously not a fully-formed theory, just thinking out loud in writing form, figured I'd throw it out there