Since receiving ballistics-tracking software from the Bureau of Alcohol, Tobacco, Firearms and Explosives in October, Savannah-Chatham police have identified about 160 potential shell-casing matches. On Wednesday, the ATF recognized the department’s forensics investigators for their work. Special Agent Tim Graden, the supervisor of the ATF’s local office, said NIBIN is a tool that can help reduce firearm-related violent crime. The automated ballistic-imaging system is used by 180 departments across the United States, and it allows investigators to learn in hours whether a shell casing collected as evidence at a shooting is linked to another crime. “It it does come back, there’s a possibility we make an arrest in that case based on the particular evidence,” said Savannah-Chatham Police Maj.