Nearly 17 years after three people were abducted and shot to death in Northern Virginia -- a CIA financial officer behind an Arlington elementary school and two college students in a Reston field -- police believe they have found their killer sitting on death row in a California prison.

Preliminary tests show that DNA taken from convicted killer Alfredo R. Prieto, 39, matches samples from the two crime scenes, according to court records.

In May 1988, Veronica "Tina" Jefferson, 24, was raped and fatally shot behind McKinley Elementary School in Arlington. Seven months later, Rachael Raver and her boyfriend, Warren H. Fulton, both 22 and George Washington University students, were abducted after leaving a restaurant in the District, taken to a field along Hunter Mill Road and fatally shot. Raver also was raped.

In 2000, Virginia's DNA database revealed that the same person was involved in both unsolved cases but provided no suspects. Then, last month, came a bolt out of the blue.

Technicians in California entered Prieto's DNA into a national database. According to an affidavit filed in Marin County, Calif., by Fairfax County Detective Robert J. Murphy, Prieto's DNA matched the samples entered from Virginia's three killings.

Prieto received the death penalty for raping and killing a 15-year-old girl in San Bernardino County, Calif., in 1990. In that case, three women were abducted and raped by three men, but only Prieto's victim was shot; the other two survived stabbings.

Jefferson's father, Henry Jefferson, said yesterday that he was "speechless" when he got a call from Ray Harp, an Arlington homicide lieutenant, telling him about the break in the case. "I broke down and started crying," he said. "For a 62-year-old man, that's something." He said he had never given up hope that the case would be solved.

Deidre Raver, Rachael Raver's sister, said: "I was so happy, and I was very emotional when I found out. It was such a big release, because it has always bothered us."

On Sept. 12, Fairfax and Arlington detectives visited San Quentin State Prison with a California search warrant to take a sample of the inmate's DNA, which Prieto provided. He declined to answer questions, sources familiar with the case said.

Prieto apparently lived in Arlington with a wife and child in the 1980s, according to sources close to the investigation. Testimony at his California murder trial indicated that he was a native of El Salvador who moved to this country in 1981.

Prieto's DNA was returned to Virginia's crime lab, where it will be tested for confirmation that it matches the DNA from the Jefferson and Fulton-Raver cases. Investigators expect a final result within about a month, Fairfax Commonwealth's Attorney Robert F. Horan Jr. said yesterday.

Jefferson, 24, had been shopping at a Giant grocery store near Columbia Pike on May 10, 1988, when she was last seen. Her body was found about 2:30 the next morning.

Raver and Fulton were last seen at a Mister Day's restaurant near Dupont Circle on Dec. 4, 1988. Their bodies were found Dec. 6. Fulton's parents did not respond to a phone message yesterday.

Matt Martin, an Arlington police spokesman, said, "If it turns out this is the guy who did it and we can prove it, it's going to be an amazing story just because it's been so long." Martin said Jefferson's case, featured in local and national media over the years, is "probably our most high-profile cold case in the last 15 years."

But now comes the question of how, and whether, to prosecute Prieto in Virginia. He was sentenced to death in California 14 years ago, but his appeals there are continuing, Horan said.

Horan has begun discussions with California officials over "the mechanics of getting him back." He said Prieto's state-level appeals are not exhausted, and then he would have federal appeals.

Meanwhile, Horan said, "Virginia runs one of these [capital cases] through inside of six years. I'm trying to pursue with California authorities how soon they think he could be executed in California."

Virginia would then have to persuade California Gov. Arnold Schwarzenegger (R) to transfer Prieto to Virginia for another trial. "We're going to see if there's any practical way of getting him back here and effectively prosecuting him," Horan said.

Although Prieto has been in jail since his arrest in October 1990, it was not clear yesterday when his DNA was collected and entered into California's DNA database or the national DNA database known as CODIS, for Combined DNA Information System.

Michael Chamberlain, a deputy attorney general in California, said voters approved a measure last year that expanded the number of convicted felons in the state database.

This year, Chamberlain said, state officials "went through and collected DNA from every inmate in the California penal system," entering 70,000 samples in recent months.

Chamberlain said Prieto's DNA may have been collected in that sweep, but he could not confirm that yesterday.