shaft in that direction and newton's law of motion. >> seven men on a railroad bridge right here said when the shots were fired they looked toward the wooden fence and each of the seven said he saw puffs of white smoke come from here. >> and underneath that green tree and you can see a little puff of smoke. it looked like a puff of steam or a cigarette smoke. >> when you stop to think about it, did he see anyone with a gun on the grassy knoll? no expended cartridges were found there. not one bullet other than those fired from oswald's rifle has ever been found and linked to the assassination. >> now, there were two doctors and one priest who claim that -- who said flatly that there were entrance wounds in the president's neck. >> if the wound in the president's throat was an entrance wound, then, clearly, this would be proof that the bullet came from the front. >> mark lane has suggested that this wasn't an exit wound by the