Here are just 3 of a long list of reasons why there was no shooter on the Grassy Knoll:

1. No experienced marksman would try to hit a target moving perpendicular; it is the most difficult angle.  A moving target should be moving toward or away from the shooter, the position in which Oswald placed himself.

2. Railroad Switch Controller Lee E. Bowers, Jr. had a perfect view of the fence atop the grassy knoll.  He confirmed, “There was no one there at the moment that the shots were fired.”

3.  And from The Final Truth: