* Before the advent of the computer, comparing fingerprints collected at a crime scene with sets of prints taken from tens of thousands of criminal suspects and recorded on cards in file drawers was tedious and time-consuming. A fingerprint clerk could compare about 100 sets an hour.

Making a match was a rare event unless police had additional leads -- such as a suspect in custody who could supply prints for comparison -- that narrowed the search.

A year ago, six Northern Virginia jurisdictions joined in purchasing and installing computer equipment that compares fingerprints found at the scenes of crimes with ones stored in the computer -- at a rate of 1.3 million an hour.

During its first year of operation, the $1.4 million computer has identified 127 potential suspects in rape, burglary, auto theft, robbery and drug cases. Ninety-eight suspects have been arrested, and warrants are outstanding for 10 more.

One of those cases was eight years old, police said.

Some crimes would have gone unsolved without the new fingerprint identification system, said Fairfax County police spokesman Warren R. Carmichael.

The computer has been so successful that other local governments are eager to participate in the joint operation, housed in the basement of the Fairfax County governmental headquarters in Fairfax City.

Vienna and Loudoun County have joined the original six -- Fairfax, Prince William and Arlington counties and the cities of Alexandria, Fairfax and Falls Church -- in the program. And the U.S. Secret Service is seeking permission to join from the Fairfax County Board of Supervisors.

In the past year, the Northern Virginia system also has been linked with similar systems in suburban Maryland and the District of Columbia, giving police throughout the Washington area access to 250,000 sets of prints on file.

"I think it's a little too early to tell just what it will do," said Fairfax prosecutor Robert F. Horan Jr. "But I think it may ultimately be quite an important feature in solving crimes."