In the months after police found Jane Marbley's bullet-ridden body at the Washington Naval Yard in 1979, the odds against finding her killer were great.

A search of the office where her partially clad body was found and interviews with acquaintances failed to give police any significant clues.

The investigation was nearing an apparent dead end when a bank robbery months after the discovery of the body unexpectedly gave police their most important clue -- the gun that had been used to kill Marbley, a 26-year-old Navy Yard custodian.

Police seized the .25 caliber semi-automatic on Sept. 18, 1979, after they arrested Gregory Hall in the bank robbery. He was subsequently convicted in that case. Four months later, police charged Gregory Hall's brother, Adrian Theodore Hall, 31, of 1234 Perry St. NE with Marbley's murder.

Yesterday, a D.C. Superior Court jury convicted Adrian Hall of murdering Marbley, who was the mother of two.

Assistant U.S. Attorney Richard L. Caplan said the case was built on evidence developed by "super police work" by homicide detectives and police technicians.

"The gun is the main thing that links [Adrian Hall] to the crime," Caplan said.

"Without the gun," he said, "we couldn't have brought this case to trial."

Police were able to tie the gun to the Marbley slaying by demonstrating that the six bullets recovered from her body had been fired from the weapon.

When police confiscated the gun after the bank robbery, they followed routine and sent it to the firearms identification unit.

Technicians then made the match. Police arrested Adrian Hall after concluding that he had access to the gun.

The man found with the gun, accused bank robber Gregory Hall, was eliminated as a suspect in the murder by Detective Sgt. Elijah Wade because he had not known Marbley. Police theorized that the absence of signs of a struggle at the murder scene indicated that the killer was known to the victim.

But Adrian Hall told police that he had been involved for four years with Marbley, investigators said. Interviews with friends of the woman and Adrian Hall, who also had worked as a custodian at the Navy Yard, revealed that Marbley had begun to reject him and had taken on a new lover in the weeks before her death. Police now had a motive.

Among other pieces of circumstantial evidence were:

A coworker of Marbley's testified that he saw Hall leaving the facility a half hour after Marbley arrived for work on July 9, 1979, the day police believed she was killed. There was no reason for Hall to be there that day because he had been fired several weeks before, prosecutor Caplan argued.

A friend of Hall's testified that in a phone conversation shortly after Marbley's body was found, the defendant said he was having trouble sleeping and asked the woman to pray for him.

Defense lawyer Bruce McHale contended unsuccessfully that the evidence was insufficient to convict his client.