The Learner's Guide to Geospatial Analysis




There were attempts to geographically profile the killers, that is, predict where they would kill next based on the killer's spatial pattern or signature. Geographic profiling brings the science of geography, criminology, mathematical modeling, statistical analysis, and environmental and forensic psychology into the realm of criminal investigation. Below is a news report about Dr. Kim Rossmo's geographic profiling:

Computer Profiler Aids in Sniper Hunt

By Jeordan Legon (CNN) (Source:

Police Foundation Director Kim Rossmo says geographic profiling "provides an optimal search strategy."

(CNN) -- Software is leading the way for investigators trying to pinpoint a Washington-area sniper. Geographic profiling, developed by former Vancouver, British Columbia, police detective Kim Rossmo, tries to zero in on the suspect by using computers to track the mass of data flooding investigators' desks -- location, dates and times of crimes. The program then matches the information with what criminologists know about human nature. Rossmo told reporters his software can help police determine where a suspect lives within half a mile. "In effect, it provides an optimal search strategy," Rossmo said. Rossmo, director of the Washington-based Police Foundation, started assisting investigators in the sniper case last week. Calculating the path,his software, which was developed by a commercial vendor and named Rigel, carries out millions of mathematical equations to give investigators a better sense of a killer's "hunting area" and where he is likely to live. Rossmo said he relies on what psychologists term the "least-effort" theory. Crimes typically happen "fairly close to an offender's home but not too close," he said. "At some point, for a given offender, their desire for anonymity balances their desire to operate in their comfort zone," he said. Rossmo's system has been used by Scotland Yard, the FBI, the Royal Canadian Mounted Police and dozens of police agencies worldwide. Rossmo developed it while walking the beat in Canada and reading widely -- including a book on the hunting patterns of African lions. The geo-profiling technology was his doctoral thesis. Methods help solve serial murders Geo-profilers claim their methods have helped detectives solve about half of the 450 cases they've studied -- everything from serial rapes to serial murders. "It's the high-tech version of the pin map," said Richard Bennett, a professor of justice at American University. "The concept is simple. But you can put a lot more information in. ... It's what you do with the information that is key." Bennett said nothing takes the place of good, old-fashioned detective work but computerized geo-mapping techniques help. "The advantage is you're using computer science and computer analytic abilities to solve a crime," he said. " You don't have a big city police chief out there who isn't using some form of this mapping."

For geographic profiling to produce accurate profiles, the serial offenders must follow a predictable spatial model (or pattern). There is good reason to believe serial offenders do. Research has repeatedly shown that the majority of serial criminals travel relatively short distances from home to commit their crimes. Research has also demonstrated that the home location of many serial offenders' crimes literally surrounds their home; referred to as a marauding pattern. These are the primary reasons for the effectiveness of geographic profiling when applied to "typical" criminals. When serial offenders behave in ways that contradict these behaviors, such as terrorist activity, geographic profiling will typically be ineffective (Bennell, 2007). For more general information read Forecasting the Future of Predictive Crime Mapping. Specifically look at the section on "The Role of Theory in Predictive Mapping."

The Analytic Question

There are significant differences between a “factoid question,” which are most common in Geospatial Intelligence, and an “analytical question.” A factoid question seeks a piece of information that would can be answered with a corresponding true statement. For example:

Question: “How many miles are between two shooter events?”

Answer: “There are 5 miles between events.”

In general, a factoid question usually has just one correct answer that can be easily judged for its truthfulness. Answers tofactoid questions are important as evidence but are not the focus of an analytic effort. Data foraging provides factoids (or evidence), small but potentially important bits of information.

In contrast to a factoid question, an analytical question has a less certain relationship with expected answer. For example:

Question: “Who is the DC Shooter?”

Answer: “The shooter could be a foreign terrorist or a serial killer.”