D, Clay Grimmer, and Arthur Burns went to the home of Mr. and Mrs. Oscar Schmidt. After cutting the telephone wires on the outside of the house, D and Burns proceeded onto the front porch of the home. Both men were armed. d carried a 20-gauge sawed-off shotgun and Burns had a pistol. The Schmidts' bedroom adjoined the porch. D remained on the porch adjacent to the windows. Burns broke the windows and stepped through them into the bedroom. D pointed his shotgun and a flashlight into the bedroom. Burns had entered the bedroom, Walter Schmidt, the son of Oscar Schmidt, entered the bedroom from another portion of the house. Oscar Schmidt was able to seize his pistol and fire it at D. The bullet struck D's right arm, and he claimed this caused an involuntary muscle spasm in his trigger finger which resulted in the discharge of the shotgun, killing Walter Schmidt. D took a deposition from the neurologist who treated him for the injury. The doctor concluded it was possible that the bullet wound caused an involuntary muscle reflex resulting in the discharge of the shotgun. The trial court ruled in limine that even assuming D's theory to be true, it would not present a factual defense to mitigate the first-degree murder verdict required under P's felony-murder rule. D was convicted and appealed.