Trajectory analysis of the final JFK head shot is said to be calculated in error in the Warren Commissions’ analysis. Its angle could not have come from the 6th floor where Oswald was perched. Warren does agree that it came from behind though.
There were two men on the 5th floor underneath Oswald, Bonnie Ray Williams & Harold Norman. They heard all three shots and Norman, who was directly under Oswald, heard the cartridge case hit the floor. It was Oswald and only Oswald.