Crime linkage systems evolve to stop
In 1999, a young orphaned girl was snatched from Haiti and smuggled into Miami where she was forced
to work as a servant as much as 15 hours every day. She was never paid, was not allowed to go to school,
and was occasionally beaten and subjected to other inhumane treatment. She finally managed to escape in
2005, according to the Federal Bureau of Investigation.
While it’s impossible to gauge covert activity with any accuracy, the United Nations estimated in 2008
that nearly 2. 5 million people were being illegally trafficked into 137 countries, mostly for the purposes of
commercial sexual exploitation or forced labor, most of them women and girls.
Despite police efforts to address and eradicate human trafficking, the crime remains rampant, even in
the U.S. According to a 2003 federal estimate, some 18,000 to 20,000 human slaves are brought into the
U.S. every year.
Crime linkage systems can play a significant role in the apprehension of human trafficking gangs when
scant traditional evidence exists. Computerized crime linkage systems are meant to assist police in determining whether crimes have been committed by the same offender.
Tim Wedge, a forensic science professor at Defiance College, said that since much of the advertising
for sexual trafficking occurs online and in public forums, crime linkage methods can be used to provide
missing clues for investigators.
“Even if human traffickers move around, there should be unique identifiers in their online postings, such
as characteristic word usages and digital images,” Wedge said.
Wedge said by using crime linkage methods it might be possible to isolate not only identifiers for individuals but identifiers linked, or likely to be linked, to specific activities as well, perhaps even distinguishing between involuntary sexual servitude and other services.
“With a well-designed and tested database of identifiers and a good Web crawler, millions of online ads
could be searched, with likely offenders flagged for closer scrutiny and further investigation,” Wedge said.
Crime linkage systems can be traced back to the development of the Violent Criminal Apprehension Program by the FBI in 1985. ViCAP was designed to collect and correlate information about violent crimes. It
remains the largest violent crime investigative repository in the U.S.
Other, more provincial, crime linkage systems exist, including the Homicide Investigation Tracking
System in Washington state, the Homicide Evaluation and Assessment Tracking System in New Jersey,
the Sex Crimes Analysis system in Iowa, and the Major Crime File used by the Royal Canadian Mounted
Police. Crime linkage systems are also in use in Australia, Austria, Belgium, Czech Republic, France, Germany, Ireland, the Netherlands, New Zealand, Switzerland, and the United Kingdom.
The relative value of these systems centers on the data—how is it collected, who contributes, how is it
validated, and what unique identifiers are used to link an object or individual to an event. The more contributors enlisted, the more useful data is aggregated. The more valid data collected, the more likely useful
associations can be made.
“For a crime linkage system to be strong, you ideally want universal adoption by both users and contributors,” Wedge said. Wedge said data validation can be problematic, since the more people you have
feeding the system, the more complicated validation becomes.