Matching the fingerprints of criminals is losing its hands-on approach, thanks to computer technology.
Previously, when someone was charged with a crime, a technician would comb through stacks of fingerprints, visually comparing those on file with those taken from suspects in unsolved crimes to see whether there was a match.
But now, a computer scans a fingerprint database and in minutes, suggests up to five possible matches. The $2 million computer system, called the Automatic Fingerprint Identification System, or AFIS, is housed in the Northern Illinois Crime Lab in Highland Park. Although installed about three years ago, the system has only become fully operational recently.
Starting with the thumbs, the computer studies the various ridges of the finger and notes where the ridges end or branch off. A technician compares the prints more carefully, making a final call on whether there is a precise match.
“It’s specifically designed to match and verify incoming arrest fingerprints against historical prints that are stored in the database,” said AFIS director Forest Grandi. The system, which can store the fingerprints of up to 200,000 people, currently has on file the prints of about 115,000 people from Lake, Cook and McHenry Counties.
The prints were obtained from known criminals and from average citizens who had to submit fingerprints to state agencies for such things as jobs or business licenses.
To date, the system has come up with five “hits,” or precise matches. Four helped link suspects in unsolved burglaries while the fifth match helped to solve an auto theft case.
“It was great,” said forensics graduate student Mark Mills, who got one of the hits. “I was skeptical of this type of thing until I saw it happen. There’s so many prints in there. When it comes out with a hit, it’s amazing.”
The crime lab gathers prints from 47 police and sheriff’s departments in Lake, Cook, and McHenry Counties. But requests for possible matches pour in nationwide. Mills said the lab was even asked to search for a possible match to the “Green River Killer,” a suspected serial killer in the Pacific Northwest. That inquiry came up empty.
While crime lab personnel have high hopes for the system, some law enforcement officials remain doubtful. Waukegan police are considering withdrawing their financial support for the system, department officials said. There are 47 police and sheriff departments in Lake, Cook and McHenry Counties that pay to put fingerprint cards in the system and have the computer search for matches.
