Come on guys, how can Bertram be Red John?? If someone is bald, he doesn't have short straight hair. And he doesn't have a soft voice, it's the opposite. If Bruno Heller chooses him, he has a lot of explaining to do because it all doesn't make sense at the moment.
In fact, the only person who has a gentle voice and short straight hair is Haffner. I know people here come up with complicated theories and clues, but sometimes we just have to look at simple facts.
But I'm starting to think like hundreds of others here, that Red John is not someone from the list.