An automated fingerprint identification system (AFIS) is a complex computer database that reads the whorls and ridges of an individual fingerprint. Long accepted in law enforcement, fingerprints are still considered the surest evidence of a suspect's presence at the crime scene or contact with the instrument of the crime. AFIS technology has made prints an even more powerful tool, but, as one of the most mature technologies in law enforcement's modern arsenal, AFIS systems are undergoing a metamorphosis.

This is the second of two parts about AFIS. The first part ("The Latent Potential of Latent Prints," Government Technology January) told the history of AFIS-- where it started and what it does.

Two Types of Prints

There are two types of prints. The first, nicknamed 10-prints, are taken when someone is arrested for a crime. The 10-print card records the fingers, thumbs and a palm print on a large index card. These prints are carefully taken, clear and easy to read, and make up the bulk of AFIS data available today. Originally, all prints were created on the cards and scanned into the system, but today, more agencies have acquired digital finger- and palm-print readers that increase the quality of the prints in the database. The second type of prints are called latent prints. These are the prints that suspects leave at the scenes of their crimes, and they are often partial or smudged, requiring more detailed computer analysis. Latent prints from the scene of a crime are scanned into the AFIS system, which checks them against all other prints in the system. Usually within moments, the system will kick back a list of possible matches. From that point, it is up to the investigator to examine the prints for a match.

Local Databases Expanded by Links

Once isolated in locally held databases, AFIS data is now linked in a variety of ways, including national, statewide and regional networks. Many cities are, in a move uncharacteristic of law enforcement, giving up their own fingerprint systems and turning them over to the states, thereby creating larger databases while unburdening themselves of the high cost of keeping up with the rapidly advancing technology.

The standardization of 10-print technology, required by the National Institute of Standards and Technology, has led to a national database, maintained by the FBI, that is accessible to state and local law enforcement. Most investigators believe that the larger the database, the more likely there is to be a match. Still, as with any cutting-edge technology, there is some debate.

"The best way to look at that issue is as a pyramid. The bottom of the pyramid is the broad base, the bulk of your work, and it is all done locally," said Ken Moses, the former San Francisco Police Department investigator who helped pioneer AFIS in the early 1980s. "Then there is the next tier, which might be adjacent jurisdictions. For San Francisco, there are many cases where the bad guy might have a link to Oakland. Then there is the next tier, statewide, but there will be fewer cases that will benefit from a statewide search. By the time you get up to the level of the FBI, there is a very small volume of cases that benefit from searching there.

"The fact is that most criminals are local. They may travel across the Bay Bridge to Oakland, but they aren't suddenly going to go to Idaho. There are exceptions to that, especially in the realm of con artists, but the rule holds: Most criminals are local."

Most in law enforcement agree, but in an age dominated by easy air travel and loose family ties, the bad guys, like everyone else, are taking to the open American road. It is not as unusual as it once was for people of