The point has been made that Sitzman was a better witness than Holland because of her elevated position and close proximity to the fence. I think there is one relative fact missing here.
Both were looking at the limo during the head shot. The shooters position behind the fence was only 10 to 15 degrees off of Holland's line of sight. But from Sitzman's position the shooter would be about 120 degrees away from her line of sight to the limo and the puff of smoke about 90 degrees away
The human field of vision is about 195 degrees. So looking straight at the limo would allow Stitzman to see about 100 degrees to her right. She could have easily missed the initial event.
Found this quote on Sitzman's Wiki page but can't trust it without verifying it. Anyone familiar with this statement?
"Sitzman stated, "I have no qualms saying that I'm almost sure that there was someone behind the fence or in that area up there [near the fence], but I'm just as sure that they had silencers because there was no sound."[14]"