Unless it can be somehow established beyond a reasonable doubt that he only fired one round, it’s possible he put one round into her head and then fired a second round into the floor to generate an “accidental discharge” alibi.
Are there any indications of another bullet impact anywhere else in the room?
I get your point, but how do you shoot a person in the head from 10 feet with a .223 and have it fragment in their skull?
And nothing was mentioned about any other bullet impacts anywhere in the room.
Good thoughts, though.