I have a theory that will answer all of our doubts.
Bruno Heller threw random clues around which he couldn't put together even if he wanted to......... as the clues piled up, it reached a point where things got out of hand and he ended everything in an instant to cover up the fact of what a fucking failure he is as a producer and writer.

I want Red John back but all hope died when the season finale had only that idiotic love crap as a main story.