MO: Domestic Defense, Father Kills Son to Save Mother

Captain Doug Wendel said they found a 29-year-old man had been shot to death in the home.

Officers learned the man had been drinking, got into an argument with his mother. Hearing the commotion, the father walked into the room to see his son choking the mother on the floor. Police said the father tried to get his son off of her and eventually struck him with the butt of a handgun.

Police said the son threw his father across the room and threatened to kill him, at which point the father opened fire and struck his son.
More Here