The other key grassy knoll data point is that when the folks ran up towards the top of the knoll they were greeted by Secret Service agents who showed identification and explained that everything was under control.
Of course there were no secret service agents at the top of the grassy knoll that day.
Yes, and the evidence given by the (unfortunately deaf-mute) Ed Hoffman, who saw a man toss the rifle he was carrying to another man who was dressed as a railroad employee; that man then breaks the rifle down and stows it in a toolbox.
Mr Hoffman's testimony comes across as shaky because of his physical infirmity. Given the prejudices of the time, it was easy for law enforcement to dismiss him. But I've listened to him several times, and to me he comes across as mentally sound, and articulate, and intelligent.