They all overestimate the realm and rigging of the human intellect, or to be more precise, the binary functioning of that human capacity. People say the odds of a loner carrying off the assassination of a leader of a free world are slim,and therefore is an argument for multiple conspirators. This argument betrays an assumption about the fitness of binary thinking to evaluate the world. In fact the plans of men are flimsy at the best. Darn dumb luck explains little except the liklihood of man's plans occasionally appearing efficacious.
My comments are meant to illuminate not the heroes or villains -- little difference from a certain perspective -- but how the logic of any theorist can go astray. I of course know nothing about what happened, but something about how people think and what they are loathe to investigate within themselves.