How do we know this supposed "hole" was caused by a bullet? How do we know it was a hole and not a crack?
Robert Frazier of the FBI testified that he examined the limo. He said this about the windshield (this is from his testimony in the Clay Shaw trial).
Q: Did you find anything unusual about the windshield and if so, please describe that condition?
A: The windshield was partially broken in a star-shaped fashion, that is there was a crack in the windshield. I made a specific examination of it to determine what caused the crack. I found on the inside surface of the windshield a deposit of lead which had been forced against the glass and had splattered and as a result determined the glass had been broken by the impact of a projectile striking the inside surface of the glass and fracturing the windshield in the outer layer.
Q: Upon what did you base your determination that the glass had been hit by a projectile hitting the inside rather than the outside?
A: As a result of having examined hundreds of pieces of glass which have been broken in a known fashion, that is by a blow delivered in a known way, it is possible by studying the radial cracks or fractures emanating from the point of force to determine the side of the glass on which the force was applied.
Using the stress lines left on this glass at the time the glass was broken and caused by the object which broke the glass it is possible to determine the direction the force was applied. This examination of the cracks showed that the pressure had been applied on the inside surface.
Q: Now the opinion which you formed as to which side of the windshield had been hit, Mr. Frazier, was that a definite opinion or was there any doubt in your mind as an expert?
A: It is a definite conclusion.
Full testimony is here:
http://mcadams.posc.mu.edu/russ/testimony/frazrsh.htm