No-one liked o'laughlin very much. He seemed annoying and everyone hated how he "stole" van pelt from rigsby. So what does bruno heller do? He makes o'laughlin the fbi mole who gets killed at the end of season 3, much to everyone's delight.
So with that in mind, you can see why bertram has to be red john. He is for sure the most annoying character now that o'laughlin has gone. Type in "gale bertram" into youtube and click on the second option "forget about jane". Gale bertram is red john because:
1) He is annoying, so it will be a satisfying finish for the audience if he was red john and killed by jane at the end of the series.
2) He is powerful, being the cbi director.
3) Although he doesn't fit the description of red john by rosalind harker, the man she was describing was likely an accomplice, a profile bruno heller used to throw us off from the real red john - bertram.
4) He both hates and admires jane at the same time, which fits the character of red john.
5) I am usually successful at making predictions with crime shows, so if i say red john is gale bertram then he probably is red john.
