Yes, one of criminal negligence, but not murder or manslaughter. Williams obviously had an ND, a Negligent Discharge, (and his GPMG should never have been cocked in the first place of course). He should have had the decency and integrity to own up and admit his appalling mistake and to take what punishment was coming to him, which I doubt would have been too onerous, a suspended sentence probably. Instead, he and his mates lied about what had happened and the Judge in turn gave him the benefit of considerable doubt, which he didn't deserve.
Your attempt at whitewashing a brutal murder of an innocent child by an occupying foreign army sarge is appalling to say the very least.