More homework

The topic tonight in my Public Information Technology class is GIS (Geographic Information Systems). So I figured I’d talk a little about Geographic Profiling…

PA 542 – Public Information Technology
North Carolina State University
Assignment 11

April 19, 2005

Subject: GIS Applications

Sources: 1998 lecture by Dr. Kim Rossmo on Geographic Profiling for the UK’s National Criminal Intelligence Service.


While working as a patrol officer for the Vancouver police department, Constable Kim Rossmo became interested in geographic mapping tools that would assist officers in solving serial crimes such as arson, murder, rape, burglary, robbery and other volume crime. Rossmo later completed his doctorate in criminology at Simon Frasier University. He studied under Paul and Patricia Brantingham, pioneers in the use of GIS for law enforcement purposes. The Brantinghams developed theoretical models that could anticipate where crimes may occur based on statistics concerning offenders. Rossmo’s thesis inverted the question, asking: If you knew where crimes occurred, could that give you information about where offenders might live?

Based on his research, Rossmo developed (and subsequently patented) the Criminal Geographic Targeting model (CGT) and termed the phrase “Geographic Profiling”. Rigel, the computer system used for geographic profiling, incorporates geographic information systems, database manipulation, imaging and algorithmic formulas. It is an information management strategy used to assist investigators in solving crimes.

In 1998, Dr. Rossmo addressed the National Crime Intelligence Service in the United Kingdom about his work in Serial Profiling up to that point.

Geographic Profiling

Geographic Profiling is concerned with mapping and probability. Psychologists often talk of the “least effort principal”, the idea that human beings don’t go further than they have to in order to accomplish their goals. The same may be said for offenders. A series of rapes or burglaries may appear “random”, but in mathematics “randomness” has a very specific meaning. Indeed, criminals tend to commit their crimes fairly close to where they live. Geographic Profiling is concerned with this “nearness principal”. However, there is a buffer zone around an offenders home wherein they will not commit crimes. As Rossmo relates, at some point the desire for anonymity and the desire to operate in one’s comfort zone ultimately balance in an area of peak probability.

Geographic Profiling actually takes data of geographic importance in a crime and plots them as X-Y coordinates on a map. For instance, in a murder there might be four points of geographic relevance; the encounter site between victim and offender, the attack site where the crime first unfolds, the murder scene itself, and finally the location where the offender disposes the body. Four points for one murder. But there might be other relevant geographical data; and if an offender has multiple victims, the information increases exponentially.

In Geographic Profiling these data points are entered into the Rigel system. The information is used to create a “jeopardy surface”; a three-dimensional map detailing the probability of where an offender may live. On the map, the area of probability would be reflected on the Z-axis, the contours on the topological surface would give you the area where the offender is most likely to live.


Rossmo tested his computer based geographic profiling system against a number of historical cases, including the murders committed by Clifford Olson. Olson is Canada’s most infamous, convicted serial killer. He murdered eleven children and was responsible for a number of sexual assaults in British Columbia in the 1980s. The geographic profiling system produced a map that pinpointed a foursquare block area around Clifford Olson’s home.

Though Geographic Profiling achieves much of its cache from celebrity cases such as that of Clifford Olsen, the system has many other practical applications that – though not as glamorous – are equally useful to law enforcement.

Consider that a typical criminal investigation can generate thousands of leads and suspects. The “Green River” murders generated over 18,000 suspects. In a decade investigators where only able to work through 12,000 names. Geographic Profiling can be used to prioritize information based on the locations where crimes occur. Examples include zip codes prioritization being used to do mailouts to the public. Searching DMV records based on locations. Blanketing police patrols in areas of high crime.

Rossmo cites one example where Geographic Profiling was used to solve a series of thirty-two armed robberies that occurred in the course of a year in Vancouver. The system created an area of probability where the offenders lived. When the next armed robbery occurred police where not only sent to the scene of the crime, but to that area of probability. The offenders were apprehended and the robberies stopped.

Beyond 1998

Approximately 200 crime analysts have been trained on the Rigel system. Today Geographic Profiling is used by police agencies across North America and Europe. Kim Rossmo is currently a research professor at the Department of Criminal Justice at Texas State University-San Marcos. Shortly after giving this lecture, Rossmo warned about the disappearance of more than 50 women from downtown Vancouver’s East-side prostitution district, suggesting a serial killer was likely at work. In 2002 Robert Pickton was arrested and could ultimately stand trial for the murders of 32 of the over 70 Vancouver women.


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