The term AWOL (absent without leave) is used throughout this episode. That term is generally used in the Army. Since John Mala is in the Navy, the term unauthorized absence (UA) would be used.
When Johnny and the SP are struggling, the .45 is in the sailor's right hand. So the bullet would have entered his skull from the right, as the post-mortem showed. But in McGarrett's reconstruction of the crime scene, the bullet clearly comes from the left. This trajectory matches where the bullet was found, but not the entrance wound.