Howard Donahue (1922-1999) was a noted gunsmith, weapons examiner, gunshop owner, marksman, and an expert in the science of forensic ballistics. His expertise was mainly as one of the people who invented the science, although later in life he studied for but did not complete a Masters degree in Forensics. And he was very good at it, being regularly accepted by the courts as an expert witness, including before, during and after these formal studies.
Donahue's theory, in a nutshell:
Lee Harvey Oswald fired only two shots at President Kennedy. The first missed, but a ricochet fragment hit Kennedy, inflicting a relatively trivial but painful scalp wound. The second hit and wounded both Kennedy (probably mortally) and Governor Connally.
The third shot, the bullet that then struck Kennedy in the head, was fired by George Hickey, a Secret Service agent riding in the follow-up car immediately behind Kennedy, and presumably fired by accident.
The bullet that struck Kennedy in the head didn't behave like the other rounds Oswald fired, or like the ammunition he was using would be expected to behave. It behaved exactly like a round from an AR-15 would behave.
The entry wound for the head shot is incompatible with the calibre of Oswald's rifle, but perfectly compatible with the calibre of the AR-15.
Hickey was carrying an AR-15 at the time, and one of the agents with him thought at first that he had fired, but later decided they were mistaken.
The fragments in Kennedy's skull were incompatible with the rounds Oswald used, but perfectly compatible with AR-15 ammunition.
The trajectory of the head shot is incompatible with one fired by Oswald, but perfectly compatible with one fired by Hickey.
http://alderspace.pbworks.com/w/pag...0theory%20on%20the%20JFK%20assassination