Although speculation remains mixed about the presence of a shooter on the grassy knoll, at least one witness's testimony can be disregarded as evidence of a shooter: S.M. Holland.

“I saw a puff of smoke still lingering among the trees in front of the wooden fence."

Unless the "professional assassins" were using Civil War heirlooms to shoot at the president, smoke is not an indication of weapon discharge. Small arms have used smokeless ammunitions since the late 19th century.