He might have known. His face was turned toward the killer and that means it's possible he was looking in that direction, having been woken by barking and other noises. He was up on a bunk as you can see from photo and DS's description of "looking up." This means, to shoot him directly straight into his eye he would have had to be facing the killer. This is the only thing that makes sense to me as to how he was shot in the eye.
If he was on his back he would have been shot in the side of his head and face, if he was turned away he would be shot in the back of the head...2 Cents..
CC. how do you know which way his face was turned? Link?