Geographic profiling is a relatively new investigative support tool used by law enforcement agencies to help prioritize where to focus a major criminal investigation by using a computer program called “Rigel” which is based on the use of an algorithm named “Criminal Geographic Targeting.” When combined with some basic assumptions about human behavior, geographic profiling can be a powerful tool to help law enforcement locate and arrest violent, serial offenders.
This computer program helps law enforcement agencies focus investigative efforts by helping them manage the large volume of information typically generated from crime scene evidence. “It doesn’t solve cases,” but it helps, explains Kim Rossmo, research professor at Texas State University and pioneer in the field of geographic profiling. It is one more investigative support tool that law enforcement agencies use to focus resources. It may help locate criminals faster and easier.
Criminal Geographic Targeting
Criminal Geographic Targeting is a patented algorithm that produces 3-D “probability surfaces” that indicate the most likely area where an offender might live. The results are then displayed through 3-D and 2-D color isopleth maps. The algorithm uses critical anchor points or activity nodes to produce an isopleth map showing the most probable areas the police should target when searching for a perpetrator, explains Brent E. Turvey, author of Criminal Profiling: an introduction to behavioral evidence analysis.
Most record systems contain home street addresses, for example, these are also used to help determine where the offender might live, explains Rossmo. Geographic profiling, therefore, concentrates on the spatial relationships between the offender’s behaviors from evidence gathered at primary or multiple crime-scene locations to help locate an offender’s most likely area of residence. By focusing on the geography of the area, investigators can retrieve other clues or hints about the location of the crime, the surrounding areas of the crime and what these factors may have to do with the current location of the offender.
Geographic profiling focuses on:
- the geography of crime,
- offender hunting behavior and target selection,
- crime site typology and child murder jeopardy,
- surfaces and how geographic profiling works,
- the relationship to linkage analysis and psychological profiling,
- case examples, and
- investigative strategies.
Crime-scene Data Collection
The geography of the crime is where crime-scene data is gathered which is later used to help predict where the offender may have gone, where the offender lives or may be hiding. Offenders create a “buffer zone,” explains Turvey, which is the area directly around the offender’s home. This buffer zone serves as a safety zone for the offender, presumptively because this reduces the likelihood of being discovered or recognized. Most crimes are committed in areas that offenders are familiar with or are close to. This reduces the travel distance for offenders who commit crimes and hide. By mapping the geography of the area and displaying it in 3-D format, investigators are able to further analyze the crime scene and near-by locations to help focus the investigation. When combined with psychological profiling, states Turvey, investigators can further analyze the offender’s behavior and predict future behavior which may help locate them.
Least Effort Principle
Two primary theories about human behavior are used with geographic profiling, explains Turvey. The first theory is called the “least effort principle.” This principle states that when given a choice, people will choose the option requiring the least amount of effort. This means that people are basically lazy and will do what is easiest or requires the least amount of effort to accomplish a goal or complete a task. People basically want instant gratification for whatever they do and will seek the easiest or fastest method to satisfaction.
Distance Decay Theory
The second theory is called the “distance decay” theory, states Turvey. This theory states that crimes will decrease in frequency the farther an offender has to travel to commit a crime. In other words, if criminal behavior requires traveling too far, criminals will do it less often. Criminals, like most people, will find the easiest way to satisfy their needs.
Necessity for Psychological Profile
Geographic profiling provides law enforcement agencies with one more investigative tool and a few more techniques to help solve crimes. However, “without benefit of a psychological profile,” argues Turvey, geographic profiling is limited.
One criticism Turvey has of geographic profiling is that it “ignores overall behavioral evidence and case context.” This means, according to Turvey, that geographic profiling does not distinguish between two or more offenders operating in the same area and, therefore, “the inferences regarding offender anchor points and spatial behavior must still be drawn by the analyst.”
Geographic profiling, therefore, is not a quick-fix solution to crime scene analysis either. It is, however, one more “support tool” and investigative technique that can be used to help analyze geographical data and human behavior that may help solve crimes more quickly and with accurate results.