How and Why the Z-film was altered

[LR Trotter]

I can appreciate what you said about the sewer. What about the badgeman?
Wilson also believed that a bullet hit the throat from the front, while Jack White
did not agree with that theory, he argued that a frontal bullet could have not pierced the collar
and that a bullet did not penetrate the neck tie.
Jack wondered if a fragment of glass from the windshield bullet had penetrated the tie.
Someone else had suggested that the wound in the throat was caused by a piercing needle with poison at Parkland
to ensure the death of the President, who could have been dangerous if allowed to survive even with heavy wounds.

I'm certainly no expert, but based only on the statements made by Mr and Mrs Newman, Mr Brehm, and Mr Zapruder on the afternoon of 11/22/63, I find it hard to believe that JFK was still alive by the time the limo passed under the RR underpass leaving Dealey Plaza. And, I wonder if a bullet/object penetrating the limo windshield possibly caused a reaction by the driver to stop/slow momentarily creating an easier to hit victim. Maybe a signal near the victim for a shooter from the front?