It appears to me that Lee Harvey Oswald was not the only gunman to shoot President Kennedy. According to documentaries of this event, there was a second gunman on the grassy knoll to the left of the Dealey Plaza book depository, looking directly at the president as he passed by.
Proof of this grassy knoll bullet hitting the president is when his head is thrown back — evidence that the bullet hit his head from the front of his body. Oswald shooting from above could not have caused this.
Unfortunately, this grassy knoll gunman has possibly died of old age.