list three things one can deduce from the position of a cartridge cartridge case and bullets at a crime scene

Just from the position of cartridge cases and bullets, it is possible to deduce what kind of firearm was used in the crime (for instance: whether it was a small pistol or a larger weapon such as a rifle), the shooter's possible position (the place where the firearm was being fired during the crime), and the shots' trajectory (if the bullets have penetrated any surface or object before hitting its targets or stopping).