I've been considering Max Winter (played by Jack Coleman) a suspect since realising it was him who gave Jane the gun he used to shoot Timothy Carter. He could be either Red John, or one of Red John's followers.
First, the problems with the theory:
- Jack Coleman is 6' 2" (RJ is thought to be just under 6 foot)
- Jane doesn't shake hands with Winter (though they could always add a flashback)
Now, the points that have piqued my interest:
- In His Red Right Hand, where it's revealed Red John made a mistake, we find out that Carter Peak was buried in concrete on a construction site. Max Winter is a construction manager.
- Max Winter has lost his wife. A recurring theme with Red John is that he turns people close to a murder victim in to his followers (e.g., Lorelei Martins). The loss of his wife puts him in this position (either as Red John, or a Red John follower).
- In the episode where Max Winter appears, he plays some mind games with Jane and generally gives the impression he has an even darker side to him.
- Bruno Heller once gave a clue about Red John saying he likes the cold. Winter would fit.
- He gave Jane the gun. By the end of season 4, it's clear Red John is toying with Jane (e.g., trying to turn him in to a follower), and I think giving the gun was the first part in doing that.
