Our speaker of the day was Darrell Smith of the Bureau of Alcohol, Tobacco and firearms (ATF).  Darrell has been with ATF since 2008 after a long career in police work. He heads the Crime Gun Intelligence Program of the ATF.
           Darrell Smith with Harvey Clark
Darrell told us that "Every Gun Tells a Story" - it has a make, a model, a serial number, bullet casings, etc.  He described the National Integrated Ballistics Information Network (NIBIN) that allows automated ballistics evaluation of shell casings.  The marks on a casing are equivalent to a fingerprint and are unique to a given weapon.  Casings found at a crime scene are entered into the system that then looks for matches to known casings.  In this way, crimes can be related and crime weapons indentified.
Gun seized in legal arrests are fired 3 times and the casings then entered into the system along with the weapon's description.
Phoenix has three of the NIBIN machines, Mesa one and Tucson one.  The Phoenix office trains 21 other agencies in the use of NIBIN.  The computer provides possible matches which are then compared to the crime cartridge by 3-D photos and actual casings. 
Tracking down who currently owns a weapon can be a long process, but is usually successful.