I think Red John is a cult of serial killers and all of the members are Red John. Timothy Carter was a Red John and McAllister was also a Red John. That's why when Carter and McAllister both say they were Red John Jane(the human lie detector) believes them    because they both believed they were each Red John     I think that maybe McAllister was the Red John who killed Jane's family but he was ordered to do it by the real Red John that's why he blinked that he was sorry for killing his family