The exact Zapruder frames that would have dis-proven a late first shot, Z208‒Z211, were spliced out by the FBI or LIFE magazine at the FBI’s behest. They then ignored three years of public pressure before claiming it was a “lab accident.”
This long-delayed denial was first mentioned to only one reporter, Richard H. Levine of the Baltimore Sun and timed to be published on the last business day before Christmas to bury the story. The Hoover FBI manipulated the media and therefore public opinion.
The FBI are the only ones who could have possibly spliced the seven frames out of the Towner film and they did the same with the Zapruder film and for the same reason: to cover up what they knew was a very early first shot.