Deadly force is justified to stop a rape or murder. This wasn't a case of vigilante justice. It was a case of a man stopping his daughter's attacker in the act. The guy didn't deserve to die, but that is the gamble you take when you rape someone.
Even if the open windows of science at first make us shiver after the cozy indoor warmth of traditional humanizing myths, in the end the fresh air brings vigor, and the great spaces have a splendor of their own - Bertrand Russell