He, his parents and his lawyers will find some lame excuse for his behavior. They'll blame it on his drug use, which he just couldn't control. They'll blame it on his upbringing. They'll blame it on social pressures. They'll blame it on anything they can so this poor boy won't have to face up to his actions.
Nobody has the nerve to point a finger at the person responsible.
It's easier to blame a small machined piece of steel. It can't talk back. People have been inventing ways of killing other humans since the cave man days when a caveman first bashed in the head of another caveman, then they found out that a club was more efficient because it provided a longer reach with less chance of the person holding the club getting hurt. So the next guy gets a longer stick with a point on it and used it as a spear. Certain refinements followed by adding feathers on the back of the arrow to make the arrows flight more stable and predictable.