Did you even read the story??? Obviously not.
Dragging the bodies has nothing to do with anything... he probably thought there were more and so he moved the bodies. And that last shot that you feel you need to complain about was a mercy shot. He shot her a couple more times after she laughed... which is where the breaking point was of her being able to be kept alive. With plenty of bullets in her, it was the most moral thing he could of done... give her peace.
You fail to realize that he could of done much much more out of anger... he could of raped both of them, he could have tortured them... that's malice... he put the girl out of her misery... that tells me that he felt sympathy.
How about you make some valid arguments?