Crime mapping is a technology-based analytic method widely used by crime analysts, strategists and planners, and operational officers and policymakers in police and other law enforcement agencies to identify, detect, map, and display the spatial and, often, the temporal distribution of crime incidents and crime patterns. By identifying the locations and the times at which crimes have already occurred, the capacity of crime mapping analysis to recognize ongoing crime patterns and trends has great predictive value in terms of focusing police activity and police resources at the locations where they will have the greatest impact in reducing crime and hence increasing security. This entry reviews crime mapping techniques and discusses the benefits as well as concerns associated with its use, including civil rights and privacy concerns.
Police and law enforcement entities have long used rudimentary crime mapping processes involving paper-based “pin maps” or acetate cover sheets with color-coded “dots” to depict the spatial and temporal distribution of crimes on a local level. Despite their low-tech nature, Dale Peet argues that these “pushpins on maps” are nevertheless a form of geospatial analytics and have been practiced for decades. These manual processes have inherent limitations, however, including the challenge of plotting the distribution of specific criminal events over extended periods of time. Paper-based mapping processes are also problematic in terms of identifying the particular crime characteristics (e.g., specific modus operandi or descriptions of perpetrators) that are critical elements in defining crime patterns and in differentiating between a mere cluster of crimes and an actual pattern of crimes attributable to a single offender. In conjunction with expansive linked data sets containing these and other critical crime characteristics and elements as well as temporal and location data, sophisticated mapping software can overcome these limitations to permit highly accurate and highly refined spatial and temporal analysis of crime.
The Compstat crime control paradigm is based on four basic principles of crime control: (1) timely and accurate crime intelligence; (2) effective strategies and tactics; (3) rapid deployment of resources; and (4) relentless follow-up and assessment. Crime mapping is an essential element in operationalizing each principle. Most notably, crime mapping is used in conjunction with other data sources to develop timely and accurate crime intelligence. After identifying a robbery pattern involving a specific modus operandi, for example, a crime mapping capability linked to an offender database can identify probationers, parolees, and others who have operated with a similar modus operandi and live or work in proximity to the robbery pattern. While this example of crime mapping does not provide probative evidence of guilt, it is a useful investigative tool to limit the pool of potential suspects. For the same reason, overreliance on crime mapping for investigative purposes could raise questions of civil liberties violations related to profiling.
Given its potential to provide crime analysts, strategists, and operational personnel with a sophisticated and nuanced understanding of the spatial and temporal relationships between crime incidents, crime mapping has become a prominent feature of advancements on the basic Compstat model, including intelligence-led policing and the evolving field of predictive policing, which uses crime mapping and advanced algorithms to predict, with a reasonable degree of certainty, where crimes are likely to occur in the future. Law enforcement activities, in response to predictive policing’s capacity to forecast when and where future crimes are likely to occur, have raised a variety of legal and ethical issues, including questions of entrapment.
Geographic profiling, an innovative analytic technique pioneered by former Vancouver Police detective Kim Rossmo, also uses advanced crime mapping techniques to examine the spatial relationships between the locations of serial crimes or crime patterns (including serial murders and serial rapes) and the characteristics of the surrounding area, particularly transportation routes. This analysis is based in part on complex statistically based presumptions that offenders tend to operate in areas that are familiar to them and in relative proximity to their residences or to places they frequent, and it can assist investigators in focusing their investigation on potential suspects living or working within a specific area or neighborhood.
Crime mapping often incorporates data sets that include data on geospatial features other than crime incidents as a means to explore the relationships between crime, place, and other variables. These data sets might include sociodemographic data to plot population density or the economic features of an area, the locations of specific types of businesses in an area (e.g., banks, convenience stores, ATMs, and other businesses that might attract criminal activity), public transportation routes and facilities, critical infrastructure, schools, parks, and the locations of previous arrests for various crimes. To aid in the investigation of a rape or sex crime pattern, for example, analysts might overlay the addresses of known sex offenders. In line with broken windows theory, advanced by James Q. Wilson and George Kelling in 1982, data concerning public order offenses, locations where graffiti proliferates, abandoned buildings, and other “broken windows” features that contribute to criminogenic conditions can also be imported and displayed. Crime mapping software can overlay these and other relevant data on plotted crime locations to discover previously undiscovered relationships between crime and place. Analysts might, for example, discover a relationship between abandoned buildings and street robberies and adopt a strategy that addresses abandoned buildings as a means to reduce robberies.
Although several criminological theories that have emerged from academic research serve to explain the reasons why relationships may exist between crime, time, and space, it should be noted that the growth, development, and expansion of Geographic Information Systems–based crime analysis were primarily driven by the practical demands of operational law enforcement rather than by academic theory. Innovative crime analysis and practical crime mapping matured as a function of the increasing demands placed on police and law enforcement agencies for effective crime reduction.
The criminological theories that serve to explain the social causes for the relationships between crimes and places include routine activities theory, which was developed in the late 1970s by Lawrence Cohen and Marcus Felson. Routine activities theory observes that a criminal transaction requires the victim and the perpetrator to both be present in the same activity space at the same time, and that in the course of their routine daily activities individuals tend to operate within a specific activity space. Another important theoretical position is environmental criminology, a set of principles first articulated in the early 1980s by the Canadian criminologists Paul and Patricia Brantingham, which asserts that crime occurs from the confluence of particular geographic, temporal, and legal factors as well as the characteristics of the offender and the victim. Rational choice theory, developed by Ronald Clark and Derek Cornish in the late 1980s, takes an essentially economic approach to explain crime, asserting that offenders decide to commit crimes as a result of an idiosyncratic cost-benefit analysis made within a framework of availability and opportunity. The environmental variables entering into the decisions include risk of detection, the perceived value of potential costs and benefits, and the availability of a suitable victim.
These theories and perspectives, along with broken windows theory’s focus on the criminogenic nature of an environment in which public disorder prevails, share a common recognition of the importance of place in the crime equation. Crime mapping permits a sophisticated and nuanced practical application of this observation, a more robust exploration of the relationships between criminal incidents, and the identification of effective strategies to detect, deter, prevent, and investigate crime.
Despite crime mapping technology’s proven efficacy in reducing crime and enhancing public safety, the technology’s capacity to quickly and precisely identify the geographic locations where crimes (and other events) take place and to link those events to a host of other data sources raise concerns that it might be misused to infringe on or violate civil liberties and/or undermine civil rights. Crime mapping technology potentially provides law enforcement and other government entities with a robust capacity to surveil the public and, by collecting and correlating various data sources with geographic information, to infringe on the privacy interests of individuals and groups. As noted, overreliance on crime mapping as an investigative tool can also put innocent people under suspicion simply by virtue of their residence location. Crime mapping technology is a powerful and effective law enforcement tool that can, like any law enforcement tool, be used properly to enhance public safety or improperly to restrict, infringe on, or violate civil liberties.
Vincent E. Henry
See also Crime ; Crime Control ; Policing and Society
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