ACTUS REUS
The actus reus requirement for murder is that Angus caused the death of a human being and that his actions were voluntary. Chris, a human being, was an innocent customer who entered the service station and was struck by a bullet from the gun which Angus was holding; he dies as a result of this strike. Voluntariness of the action needs to be established. Angus had a loaded gun pointed at the cashier; demanding money and cigarettes, there's no question that these were all conscious and voluntary acts. Chris was struck by the bullet which was discharged from the gun as it hit the floor after falling out of Angus's hand as he slips on the floor. In applying the law to the given facts, Angus did not actually pull the trigger of the gun but all his actions prior to slipping on the floor were voluntary and the death occurred in the course of his voluntary actions; regardless of his awareness or unawareness of what might occur in the course of his actions.
Causation
Factual Causation
The prosecution must show that the it was the act of the accused was the cause of death. If it wasn't "but for" Angus having a loaded gun, Chris would not have died.
Legal Causation
The prosecution must show that the accused conduct was the substantive and operating cause of death and that any intervening act did not break the chain of causation.
In R v Hallet, the accused rendered the victim unconscious and left him at the water's edge; victim died of drowning when the tide had risen; it was held that the normal operation of the tide did not break the chain of causation; found guilty. In applying this reasoning used to the facts presented, Angus was in the service station with a loaded gun pointed at the cashier, the fact that he failed to read the warning sign of the wet