What strikes me a bit off if Crooks was really hit from the back or more from the front. Unfortunately, we only have a few images available to come closer to a solution. And I can be off, of course. Sorry, for the picture again.
The red mark looks to me like if the skin goes to the outside, which is more likely for an exit wound. Most often, and judging from shooting game, the entry wound is minimal, and often you even need to search for it. The exit wound depends then on the bullet, though I don't know what military or snipers use, and I'm lacking the proper English names: full metal jacket, or tipped ones? No matter what, when a bullet exists a body, the skin goes outside, because of the strength/force.
The hair could also be blown up when it exists on the back. And also maybe he was lifting his head to look, what damage he had done, where the sniper could see him. Which is also normal after shooting, to get an overview of the scene. Depends if a shooter is used to use both eyes for aiming and only concentrates on the one eye in front of the sight or if he closes one.
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