Geographic Profiling

Criminal profiling is made up of psychological profiling and geographic profiling. The latter is a phrase coined by the Canadian criminologist Kim Rossmo in the early 1990s to describe the use of computers to generate predictions on a serial offender's place of residence or base of operations. The software used for geographic profiling—Rigel Profiler and Rigel Analyst (both created by Rossmo's Vancouver-based company), CrimeStat, and Dragnet—has changed the face of serial crime investigation in large urban centers.

It wasn't long ago that each briefing room across the country contained a map of the local detachment area and surrounding land, and on it crimes would be recorded by pins. Pin maps have a limited usefulness. If an area has heavy crime rates, the map becomes littered with holes and, with the exception of colorcoded pins, essentially only one type of crime can be plotted. Updating the map means removing the pins and losing data from the past period of crime.

In the late 1980s, on the west coast of Canada, researchers at Simon Fraser University realized that humans follow patterns in their movements. People have mental maps of their surroundings, created through experience and familiarity with the location of sources for their daily needs. This mental map contains access routes to food, school, work, transportation systems, and at the heart of the mental map is their location of primary residence. Psychologists call this theory the principle of least effort.

Around the same time, Kim Rossmo, of the Vancouver Police, started to pursue his Ph.D. in Criminology at the same university. Through an interest in hunting behavior of animals, and his knowledge of the criminal field, Rossmo formed a theory that, like animals, criminal predatory behavior could be predicted. Offenders preferred to use familiar territory for their crimes. However, their anonymity was paramount and so there would be a buffer zone of no criminal activity around their place of primary residence for fear of being recognized. Rossmo also realized that the offender must have come across his victim at some point within his own mental map area. He developed a mathematical algorithm into which he could feed information on the crime and opportunities for interception between victim and offender, and obtain a rough prediction of the area in which the offender likely resided. This mathematical algorithm was subsequently patented by Rossmo and is at the heart of his geographic profiling software.

Geographic profiling brings the science of geography, criminology, mathematical modeling, statistical analysis, and environmental and forensic psychology into the realm of criminal investigation. It replaces the pin map and "hunches" on the whereabouts of the offender with a much more userfriendly, easy to read, and adaptable output map that uses science to indicate the most likely area that police agencies might focus their investigations in order to locate the serial offender. From the Rigel software, this map can be a two-dimensional or three-dimensional rendering of the geographical area under investigation. These maps are called jeopardies and use color-coding to indicate the area of highest probability to include the offender's place of residence.

Rigel system literature states that, "A Rigel analysis starts with a street map of the study area, the geographic coordinates of the crimes, and any database that the profiler wants to prioritize." Rigel is used in conjunction with GIS (geographic information systems) and is portable and usable in any mapped area in the world.

As well as its ability to predict the location of the offender's base (being able to "reduce the search area for a suspect's home by 90 per cent" states Kim Rossmo in his 1999 book, Geographic Profiling ), Rigel software has gained enthusiastic responses from police agencies for its ability to help organize the vast amounts of data created when investigating a linked series of crimes. In the 1992 Washington DC sniper case, Rossmo aided investigators by using geographic profiling. Although the profiling did not lead to the location of the offenders, it did aid the police to the point that Assistant Police Chief Deirdre Walker of Montgomery County, Maryland, released a statement saying, "The joint task force found geographic profiling a helpful and useful tool in strategically prioritizing information in this investigation." And indeed, that is what geographic profiling is, a tool. It is a tool to be used along with other aspects of police investigations and it relies heavily upon work already done by the primary investigation team. Elly Abru, in her February 2004 article "Coordinates of Crime" published in Australia's Police News, writes, "Yoking together the power of GIS and computing, geographic profiling has enormous potential as a tool for sifting, matching, clarifying and analyzing information. It has yet to reach its peak."

Geographic profiling is most useful in tracking serial criminals. As of 2005, it is not useful for solitary crimes, crimes where offenders travel great distances between offenses, or for small rural forces where major serial crimes are unlikely. There are areas for improvement in the software, but as the field of geographic profiling continues to develop and its software capabilities continue to improve, the demand for geographic profiling technology is expected to grow.

see also Criminal profiling; GIS; Profiling; Psychological profile.