Firearms/Tool Marks


The Firearms and Toolmarks Unit examines firearms for operability and performs comparative examinations on fired bullets and cartridge cases. In addition, the Firearms and Toolmarks Unit conducts serial number restorations, distance determinations, and toolmark comparisons. At the end of 2014, after the retirement of a longstanding Firearms examiner at the Madison Laboratory, the Firearms and Toolmarks Unit transferred all cases to the Milwaukee Laboratory. To support the unit, there are four Firearms and Toolmarks positions at the Milwaukee Laboratory.


As part of firearms examinations, cartridge case images may be stored and searched in the National Integrated Ballistic Information Network (NIBIN). NIBIN is an automated database that looks for similarity in digital images of fired cartridge cases. The NIBIN unit then generates a correlation list of potential matching images for analysis. This technology can create investigative leads by associating digital images of test fired guns and evidence cartridge cases to different crime scenes.  


In addition to examining evidence, the Firearms and Toolmarks Unit is instrumental in storing and destroying both guns and ammunition in the state of Wisconsin. This project requires a lot of maintenance as there is a constant influx of both. In the last 2 years approximately 15,000 firearms were destroyed by the WSCL.


Firearms and Toolmarks : Caseload and Case Type


In 2016 the Firearms and Toolmarks Unit saw a 20% decrease in cases submitted for analysis. While Firearms turnaround time has remained relatively constant over the last three years, loss of trained analysts as well as training of few analysts affected the overall Toolmarks turnaround time.  As demonstrated by the graph below, a majority of the cases worked were related to homicides, weapons, and assaults.  Property Crimes remain the most prominent Toolmark offense type.