Who Killed Dr Black?

Primary 5/6 had a 'Murder Mystery Day' today. The class entered the room and saw an outline of a body (you can see their reaction in the short movie clip below). They learned that Dr Black had been murdered and his famous diamond stolen. They class were told about the suspects and were sent out to find the murder weapon. The pupils were told that they were the famous Belgium detective, Hercule Poirot, and were given moustaches and bowler hats. The class were asked to write the conclusion of the story.