There's multiple camera angles which captured the minutes leading up to her death, posted on major news sites like The Washington Post, so no assumption needed.
I still don't feel the shoot to kill was justified (especially as a shot in an area that would immobilize a person, like the chest or the gut, would've been safer of collateral damage vs a shot to the head, similar to the one taken, which unequivocally is a shot intended to kill), but trying to argue she was not completely and totally in the wrong is just absurd to me.