Thomas McAllister is old enough to be located in police position around the time of Red Barn.  He is related to the true leader of Visualize.  McAllister is either the son of Visualize's former leader or another type of relation.  He decided to start killing Visualize members to test himself.  He may have covered for the ex-leader (executed) of visualize (if he is not it) by showing up to help make it go away.  He may have taken the blame for the killings, and he could be covering his tracks or someone he cares about.  Robert Kirkland was onto Visualize as a Red John associate, and he ended up going crazy.  He killed people, because he thought they knew who red john is.  What he was trying to do was find his brother who he believes joined Visualize.  Brett Stiles supposedly had the sheriff investigating Timothy Farragut's (original Visualize guru) death executed, because it was staged to look like an accident.  Lisbon's mom was killed by a drunk driver, and Timothy Farragut's (ex leader of Visualize) fatal accident involved alcohol.  There is a small chance that those two are related.  However, Farragut's death was ruled an accident.  Somebody wanted retribution for Stiles executions.  Red John is possibly someone struggling against Visualize.  Jane offers Red John a chance to kill Stiles, but he must be sacrificed - or there is no deal.  Jane can make it happen, but Red John has to die for killing his wife and daughter.