There was Mary Moorman, poised, ready, and waiting for the Kennedys. And notice that, like everybody else, she is turned to her right at that point, since that's where the Kennedys were.
But, we are expected to believe that even though the Kennedys just crept by and practically stopped in front of her, that she didn't shoot their picture then, that waited until they passed her and then shot the back of their heads.
It's crazy. She didn't take this photo.
And now, Backes thinks he knows better than a physics professor where the photographer was for this picture.