For the fact there was no debris field, down range from JFK's head in line with Greerís supposed shot, and that both Governor and Mrs Conolly, who were in the car with the Kennedyís, testified they heard no gunshot, tends to exonerate Greer.
Some have said that the nickel plated revolver, was sunlight reflected onto the hair of Secret Service agent Roy Kellerman seated beside Greer, and direct inquirer's attention to a piece of the Zapruder film, that shows him with both hands on the wheel.
Certainly his body language indicates that he fired on the President, and for the fact that sunlight could have provided an illusion, does not explain why he turned around twice, nor does it tell us what it was that he recovered from under the dash.
As many experts that have declared the Zapruder film to be authentic, are matched by as many more who say there are gaps, and that some frames are missing, or have been cut and spliced back together out of sequence, or both.
So Greer is not in the clear by any means, the Secret Service team leader recalled the two men, who would normally have been standing on back of the vehicle as it entered Dealey Plaza, and allowed a wide gap to develop between the Presidential limo, and the next car in the motorcade.