The two men who apparently robbed a Chantilly bank and then fatally shot themselves as police converged on them Thursday were paroled federal prisoners with histories of violent crimes, Fairfax County police said yesterday.

Police identified the men as Richard Allen Gordon, 43, of College Park, and Francis Browne Hall Jr., 36, of Mount Vernon, and said their double suicide in a parked getaway car closed investigations of six previously unsolved Northern Virginia bank robberies.

Although witnesses have told police they saw a third man hurriedly leave the Central Fidelity Bank near Dulles International Airport after Thursday's robbery, police believe Gordon and Hall acted alone, police spokesman Warren E. Carmichael said.

The shootings occurred after police chased the suspects to a church parking lot. There the suspects abandoned a stolen car they had used to flee the bank and got in a second car they had borrowed from Hall's mother, whom police described as a Washington resident.

According to police sources, Gordon put the muzzle of a 38-caliber revolver in his mouth and pulled the trigger; then Hall did the same.

Autopsies performed yesterday found gunshot residues that indicated the wounds were self-inflicted, Carmichael said. Northern Virginia Medical Examiner James Beyer said only that each died of a gunshot wound in the head.

Carmichael said that one shot fired by a police officer during the chase grazed the hood of the first getaway car, a Ford Escort, and that the officer's second shot bounced off a curb in the parking lot.

Approximately $100,000 taken from the bank was found in two pillowcases; Gordon and Hall left one pillowcase in the first getaway car and kept the other, police sources said.

Other items found in the Plymouth Gran Fury in which the suspects died include a Ruger Mini-14 .223-caliber semiautomatic rifle used in the robbery, 194 rounds of ammunition and a speed loader for the Ruger, a police scanner, and an almost empty bottle of vodka.

Witnesses at the bank smelled alcohol on the breath of at least one of the robbers, Carmichael said.

Commonwealth's Attorney Robert F. Horan said he was mystified by the turn of events. "The intriguing part of the whole case is why these two -- who had convictions for crimes of violence -- why they didn't shoot it out. Why they decided to take the suicide route is perplexing, to say the least."

Carmichael noted that both men had served long prison terms and faced imminent arrest.

Gordon was sentenced to die in the electric chair after he was convicted of murder in the 1963 beating death of a Washington man. That sentence was later reduced to life imprisonment, plus five to 15 years for stealing $87 from the victim.

At one point, Gordon testified that the slain man's brother hired him to commit the murder, but he later recanted that testimony. Gordon was paroled in 1981 after spending about 17 years in various federal penitentiaries, according to prison officials.

Hall was convicted of manslaughter in 1975 in D.C. Superior Court and sentenced to 15 years in prison, federal probation officials said. Three years were added to his term after he was convicted of escaping or attempting to escape from prison, federal officials said.

Hall was furloughed to a halfway house in the District in June 1986 and was released on parole the following month. His parole officer at the U.S. Probation Office in D.C. refused to comment, and a spokeswoman for the office would not discuss the terms of his parole.

Gordon and Hall were at the federal prison in Memphis from 1978 to 1980, a law enforcement source said.

Police said they believe the men were responsible for two earlier bank robberies in Springfield plus robberies in Vienna, Fairfax City, Reston and a Jan. 12 robbery at the same bank in Chantilly where Thursday's robbery occurred, the Central Fidelity Bank at 1200 Sullyfield Circle. Carmichael said that police linked the two dead men to those robberies by their method of operation: The robbers always wore ski masks and used stolen getaway cars, which they abandoned near the scene, he said.

Investigators had exhausted all leads in the cases and appealed for assistance from the public through the Crime Solvers program, which offers rewards for information leading to arrest and conviction.

Police said they believe Thursday's robbery was at least the second time one of Hall's and Gordon's robbery attempts had gone awry. An attempt of which they are suspected at the United Virginia Bank in Reston failed on Jan. 12 when a dye pack in a money bag exploded, police said.