GIS is a complement to law enforcement agencies, boosting the strength to collect and store data to be used and shared amongst agencies. A map can be created to show when and where a crime occurred and the details within the crime. Once data is entered into a GIS database, the user can overlay that information with a specific crime, which may reveal the identity of the victim and/or criminal. Due to the chance that private information may be exposed, users must be aware of confidential and sensitive data.
Law enforcement agencies may use GIS to map registered offenders to compare where the offender lives and the locations of town schools. Buffers are used to observe how close an offender is to a school. Buffers are also used when mapping victims issued protection orders to reveal violations or compliance with specified restrictions.
Analysts in law enforcement agencies use GIS to look for patterns and trends to highlight suspicious events that may require further investigation, carry out various policing methodologies to reduce crime, and to forecast future crime occurrences. Most law enforcement agencies suffer from limited sources, analysts are able to use GIS to efficiently and effectively match demands for service, distributing resources after analyzing crime trends over time. GIS can model workflow and capture practices (correlating certain types of crime to a time of day or day of week). This can allow law enforcement agencies to target their efforts to specific locations while being more fully aware.
Here are several success stories how organizations have benefited from using GIS: http://www.esri.com/industries/public-safety/law-enforcement/success-stories