The series name is "the mentalist". From the wiki, here's what the definition of "Mentalism" is Mentalism is a performing art in which its practitioners, known as mentalists, appear to demonstrate highly developed mental or intuitive abilities. Performances may appear to include telepathy, clairvoyance, divination, precognition, psychokinesis, mediumship, mind control, memory feats and rapid mathematics. Hypnosis may also be used as a stage tool. Mentalists are sometimes referred to as psychic entertainers.

We all know Jane was an entertainer before. Also we have seen this a number of times ,that he has hypnotized a few people. 

So, I propose, that Jane, who always says that there is nothing like clairvoyance or psychic powers, actually uses hypnosis to make people kill other people.  He may not be Red John, but he could be the one who "Makes" RJ.. .and post hypnosis, the person doesn't remember anything, anyway! 

So there could be more than 1 person doing it...