CNN Anderson Cooper 360 January 7, 2016 02:42:00
Gun's basic examination to the tank room. why do we call it a tank room? >> because there is a large tank filled with water. >> reporter: i see that here. >> the purpose of this tank is to that we can discharge a weapon and acquire the bullet. >> reporter: where does the bullet end up? >> the bullet will travel through the watt aerocertain distance and drop through the bottom of the tank. >> reporter: the detective is firing into the bullet recovery tank. >> reporter: once a bullet is recovered, it goes under the microscope then tested for fingerprints. >> if there was any fingerprints that we...