As part of a program to help identify children who become lost or are reported missing, police in several Maryland and Virginia counties are offering to fingerprint school-age children and give the prints to the children's parents.

Montgomery County and Alexandria police departments will offer the free service beginning this weekend.

To ensure that the fingerprints would be used solely as a tracking tool, police said that parents would get the only copies of the prints. If a child is reported lost, the parents would be asked to give the fingerprints to local authorities, who in turn would give the prints to the FBI, police said.

"It will be an investigative aid on stranger abduction and parental abduction cases, particularly in cases where the parent and child don't recognize each other from photos," said Alexandria police Sgt. Ron Graves.

The services are part of a trend that police said gained national attention with the signing of the 1982 Missing Children Act. The FBI currently lists more than 16,000 juveniles as missing and counted 120,000 juvenile runaways as "located" (either found or arrested) in 1981, according to an FBI official.

"Anytime a youngster is either found deceased or unable to communicate, fingerprints would certainly be beneficial," said Sgt. Steve Hargrove of the Montgomery County police youth division. In 1982 the county recorded 1,700 juvenile runaways, Hargrove said.

"Fingerprints are the only conclusive evidence," said Montgomery Detective Ron Howard. "They never change."

Sgt. Graves said Alexandria police will suggest that parents keep dental records and yearly photographs of their children. Parents have the option of putting these items and fingerprint cards in the child's school records "to follow them through their school career," he said.

Anne Arundel County police plan to begin a similar program on May 21. Frederick County has such a program under way and Baltimore County police are discussing the idea with the county's school board.

In Virginia, police in both Fairfax and Arlington counties said that they hope to implement such fingerprinting programs by fall.

In the District, police said that a fingerprinting program for youths is "barely in the planning stage."

The program for Montgomery County residents will be available at the Public Service Training Academy, on Rte. 28 west of Shady Grove Road, on Saturday and Sunday, from 10 a.m. to 4 p.m.

In Alexandria, the service will be offered at Hamlet Community Center, 5708 Merton Ct., on Saturday, from 2:30 p.m. to 6 p.m.