Law enforcement relies on location and information. Traditionally law enforcement collects information and data to solve crimes. These data need to be placed in context of the location and time(s) that crimes occur. Maps prepared using geographic information systems (GIS) allow data analysis to investigate crime patterns. Such analysis may help identify, apprehend and prosecute suspects. GIS mapping helps balance limited law enforcement resources of people, time and money, and more effectively manages scarce resources. See Figures 1-2 and discussion below.

Law enforcement work greatly involves locations, jurisdictions and time. Crimes occur in locations; police have specific precinct or jurisdiction boundaries. Law enforcement has always involved mapping crime locations. GIS maps can replace "pin maps" with data analysis to determine criminal and gang activity patterns and the linking of databases containing incidents at addresses, frequency of accidents, time of day or day of week, and lists possible suspects based on proximity to a crime scene. Digital images of crime scenes and suspects can be linked to crime scenes as well. Gang territories can be mapped using GIS. GIS maps linked with data provide the tools to ask "what if?" and to test, many possible relationships of crimes, clues, patterns and territories.

Crime patterns can be analyzed across jurisdictions and over time using GIS. Information about individual crimes is attached to each point to aid pattern recognition, and to assist crime prevention by law enforcement resource allocation. Mapping gang territories can aid prevention and enforcement, and community education.

The following example is from the the Town of Cary, North Carolina (2001 data). Selected crime types across several 'beats' (colored blocks) are shown for an entire year: vandalism (red squares), burglary-forcible entry (green dots), burglary - non-forcible data (yellow triangles), and arson (dark blue circles). Black dots denote the location of all other crimes for this period (Figure 1). Geographic information systems (GIS) empower law enforcement investigators to look for crime patterns across jurisdictions and by time, date and location — relationships that might go unnoticed by traditional 'pin' maps (Figure 2).

Figure 1 — GIS analysis of selected types of crimes across jurisdictions. Mapping of crimes by type as in this example provides useful pattern information. Similar maps showing can be prepared showing day of week, hour of day, etc. that crimes were committed. Map prepared by ForensicGeology, Inc.

Figure 2— Crime data not analyzed by GIS analysis of selected types of crimes across jurisdictions; same area as Figure 1. Map prepared by ForensicGeology, Inc.

Additional contact information

For additional information contact Dr. Jeff Reid, P.G., CPG, President, ForensicGeology, Inc., 8401 Summerspring Lane, Raleigh, North Carolina, 27615. His telephone number is 919.618.0810. His ForensicGeology, Inc. e-mail is jreid@forensicgeology.com.

Students (NCSU university classes only) should contact me by e-mail at jreid@ncsu.edu. Students may also elect to contact me at jreid@jeffreycreid.com by prior arrangement.