Gale bertram was the first person I suspected to be Red John. After the season 3 finale I changed my mind about Bertram being Red John, and suspected 20 other people based off random theories. Now that Bruno Heller has given us 7 names to choose from, Gale Bertram being red john makes the most sense. He does have a creepy vibe about him.
Anyways, watch this video if you want proof of gale bertram being RJ =)
http://www.youtube.com/watch?v=12s2rFbX7SA
