RE: "Something moved...and he fired."
I know of two other cases where one brother killed the other while hunting. One was a duck hunting accident when a shotgun went off striking the brother. The other was a bow hunting accident that sound much like this one. One brother shot at a noise in the brush and killed his brother. Niether of the surviving boys will ever be the same again and the trajedy will live on forever. You just don't fire until you are triple positive of your target and the background. I pray for the lords help for the family.