Umm, because he fired from a concealed position behind the fence on the knoll.
He wouldn't have been concealed from Lee Bowers who had a clear view of the area behind the fence from an elevated position. People raced to that area after the shooting including some from the overpass and no one saw a shooter. Because there wasn't one.
Moreover, as I have pointed out to you before when you have argued against a grassy knoll shooter:
-- Several witnesses saw gun smoke coming from the area behind the fence on the knoll identified by the acoustical evidence as the location of the gunman.
Witnesses said they saw smoke. Gun smoke was your addition. Had it been gun smoke, it would have dissipated almost immediately before anyone could have seen it, unless of course your shooter was firing a flintlock or a blunderbuss.
-- We have hard photographic evidence that confirms the eyewitness accounts of seeing gun smoke on the knoll, i.e., the Wiegman film, which shows a small cloud of smoke hanging in the air near the fence on the knoll.
Again, you are assuming it was gun smoke.
-- Several witnesses smelled the pungent odor of gunpowder on and near the knoll right after the shooting.
That gives no indication of the source of the shots because the residue from a gunshot can and does travel from where a gun was fired. Senator Yarborough was in a car on Elm St. when he smelled the residue and there are no reports of a shot fired from Elm St.
-- Two witnesses saw a man running from the grassy knoll into the railroad yard seconds after the shots were fired.
Which witnesses? Ed Hoffman? <chuckle>
-- Dozens of witnesses in the plaza (at least 58) said they heard shots fired from the grassy knoll.
Dozens of other witnesses heard those same shots and they said it sounded like they came from the TSBD. Those witnesses are corroborated by shells and a rifle found in the TSBD and eyewitnesses who SAW a gunman in the sniper's nest. No corroboration for the folks who thought the shots came from the GK.
We still see lone-gunman theorists repeating the argument that those witnesses merely heard echoes of the sixth-floor gunman's alleged three shots. In his superb 1998 book Cover-Up, mathematician Stewart Galanor explains why the echoes argument is invalid:
Echoes are caused by sound bouncing off large, hard surfaces. . . . There are no buildings on the knoll or overpass that would have reflected sound back to confuse witnesses in Dealey Plaza. Beyond the knoll the terrain is flat with railroad tracks, while the knoll is covered with grass, shrubs, and trees that absorb sound. If there were any echoes, they would have been caused by the sound of rifle fire from the knoll echoing off the Book Depository (Cover-Up, p. 76).
I don't know what led those people to believe shots sounded like they came from the GK but I do know there is no physical evidence of a shooter there nor eyewitnesses. I also know from first hand experience it can be difficult to locate the source of the gunfire based on sound. I live in a rural area and gunfire is not an uncommon sound, especially right before the deer gun season. When I'm walking my dogs, I hear the gunfire but I don't know where it is coming from until I visually sight which of my neighbors is taking target practice. Sometimes it turns out the shots were 90 degrees or more away from where it sounded like the shots came from, and I don't have tall buildings around to create the echos.
-- Dozens of witnesses rushed up the grassy knoll right after the shooting because they believed shots came from there.
WOW! All those people rushed the GK and not one of them saw a gunman. What are the odds?
-- Seconds after the shooting, Sheriff Bill Decker ordered his officers to seal off the area of the railroad yard behind the knoll and the triple underpass: "Have Station 5 to move all men available out of my department, back into the railroad yards there in an effort to try to determine just what and where it happened down there, and hold everything secure until the homicide and other investigators can get there."
-- Seconds after the shooting, Chief Jesse Curry ordered his officers to check the area of the triple underpass: "Get a man on top of that triple underpass and see what happened up there!"
Which simply indicates pinning a badge on your shirt doesn't give one special powers of auditory perception. They can be fooled just as easily as anybody else. It's notable that Decker and Curry directed their resources to different places.
-- William Newman, a combat veteran, said he heard a shot come from behind him on the knoll and that he heard the whiz of the bullet as it passed near him. As someone who heard bullets whiz above him in the Army, I know exactly what Newman was describing.
-- Abraham Zapruder, before he knew what he was supposed to say, told the Secret Service on 11/22/63 that "the position of the assassin was behind Mr. Zapruder" (CD 87). Zapruder was standing on the pergola on the knoll, so the area behind him would have been very close to the spot identified by so many other witnesses and by the acoustical evidence.
Looks like Newman and Zapruder didn't have any special powers of auditory perception either.
