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Implementing Gunshot Detection Technology Recommendations for Law Enforcement and Municipal Partners

NCJ Number
Date Published
October 2019

This report presents the findings, methodology, and recommendations of a three-city evaluation of gunshot detection technology (GDT), a system that uses a network of outdoor acoustic sensors to automatically detect gunfire and promptly alert law enforcement officers. 


The three cities involved in the evaluation are Denver, Colorado; Milwaukee, Wisconsin; and Richmond, California. All three cities use ShotSpotter, Inc.’s GDT product, although several vendors produce and sell GDT. The evaluation documented how agencies have implemented and used GDT, as well as its impacts on shooting notifications, response times, violent-crime rates, and police-community relations. The evaluation team interviewed 46 law enforcement personnel and 49 community residents, and it coded 174 firearm-related case files in examining how each city implemented GDT. In addition, the evaluation analyzed GDT alerts, previously reported violent crime data, and calls-for-service data in assessing GDT’s impact on department notifications of shootings and officer response times for those notifications, firearm and violent crimes, and calls for service that involved reports of shooting and violent crimes. The findings on GDT’s impact on crime were mixed, both within and across sites; however, GDTs yielded cost-benefit impacts in some locations and contexts. The evaluation also identified a wide range of implementation strategies, providing insights on how agencies can implement GDT in a manner most likely to produce the intended impact. Recommendations are proposed. 3 references

Date Published: October 1, 2019