It wasn't a conspiracy, it was a cover up.

"Written by Missouri-based journalist Bonar Menninger, the book claims that when Hickey heard the first volley in Dallas' Dealey Plaza that day, he pulled out an AR-15 assault-type rifle while standing in a trailing Cadillac outfitted for the Secret Service.

The first shot by Lee Harvey Oswald (according to Mortal Error) hit the pavement. The second -- the so-called "magic bullet" -- struck Kennedy in the neck. At that point, Hickey lost his balance in the Cadillac, "Mortal Error" claims, and he accidentally pulled the trigger, hitting the president in the head.

So Hickey reaches down and grabs the AR-15 off the floor, flips off the safety and stands up on the seat, preparing to return fire," one passage reads. "But his footing is precarious. The follow-up car hits the brakes or speeds up. Hickey begins to swing the gun around to draw a bead on Oswald, but he loses his balance. He begins to fall. And the barrel happens to be pointing toward Kennedy's head. And the gun happens to go off."