Get the kids thinking.
Give a description of a crime scene and the students have to figure out what happened by asking only yes or no questions.
Joe is dead in a room. There are three sets of tracks leading into the room and two sets of tracks leading out of the room. There is a stain on the floor under Joe.
Joe hung himself. There is nothing else in the room except him, the rafter on which he hung himself, the stain on the floor, and the tracks. He had a large block of ice ordered on which he stood to hang himself. He then let the ice melt. The tracks were him, the delivery man, and his hand-cart. They brought the ice in, then the delivery man left with his cart.