His problem was not that he shot the burglars, or that he finished them off. Even keeping their bodies for a day could have been generally excused with a smooth tongued good lawyer.
His problem was that he then shot off his mouth about it to the police. If he is going to prison it is because he lacked “mouth control”.
Imagine you see two armed robbers exiting a bank with guns and bags of cash. You have a gun and shoot them both. When the police arrive, you are like a bouncy little puppy and tell them that “I gunned down a couple of n******! That’ll teach those b**** b******* that this is a w**** people’s town! Heil Hitler!”
What mistake have you made? If it is not clear to you, then you are not very bright. Everything you did up to the point of shooting your mouth off was a-o.k. Then you totally fouled up in an awful way.
How would his lawyer have explained the shot under the chin???