In the fifth chapter, entitled Three Bullets, Jennifer Paige and her sister Lisa go into the police station and find the deputy there dead. They noticed the .45 revolver on the ground that belonged to the deputy, but then she finds three expended casings on the ground. A revolver doesn't expend empty shells, it holds them in the gun until someone swings out the cylinder of the gun and empties them by hand. A semi-automatic pistol expends shell casings, but the book describes it as a revolver, and Jenny even swings out the cylinder.