So stupid, lets just assume that he really shot her for the sake of these thoughts, and its really hard to do because the thing was so staged but here goes.

The cop was standing behind the door in a little crook, semi hidden from view. It took her forever to enter and she was totally non threatening...was he the only security with a gun as this mad crowd was breaking through.....seem lke if the cop was really telling her to stop he could have come out of hiding and made his intentions clear vs acting like a sniper...didnt they already clear out the congress because of bomb scare....who was she threatening