If she used a shotgun with slugs, there will be plenty of evidence in the skeleton.
And anyone who could do that to a little kid...there are no words. That's not a "in the heat of passion" thing to do. She had to choose ammo. She couldn't pretend to herself about what she was doing and tell herself it was an oopsie, like she usually does. It does help explain her incredible quest to hide the body, though, as it's not just that she killed him, it's also how she killed him. When that is revealed, I predict her group of supporters are going to be sick. Unless they are all psychos as well.
(Psycho is not a professional term, MOO)