Citizens filed five lawsuits over shootings involving Walker. The District paid $186,701 in settlements and judgments to resolve the cases, court records show. Walker did not respond to phone calls and letters seeking comment.

Five of Walker's shootings – all in a 10-month period in 1992 and 1993 – were investigated by his supervisor, then-Sgt. Donald Gossage. In two of those shootings, citizens died.

Police regulations say fatal shootings should be investigated independently by the homicide branch. Gossage said in an interview that police officials dispatched him to the scene of both fatal shootings involving Walker. Gossage said he subsequently spoke with the homicide detectives about the physical evidence and the witness statements they were gathering, and about the status of the cases. Gossage said his role was limited to examining whether the officers had violated department policy, not whether they had violated criminal laws.

Two years after those shootings, when Walker and his partners had been cleared by U.S. attorneys, Gossage wrote the department's final investigative reports on the cases and recommended that the shootings be declared justified, police records show. Gossage said that his reports were impartial and followed department policy but that supervisors generally should be barred from investigating their own officers.

"I think the people who complete the investigative report should not be the people who work with the officer on a day-to-day basis," he added.

In another, nonfatal shooting by Walker, Gossage investigated the episode although he had been at the crime scene directing Walker's activities; in another nonfatal shooting, Gossage helped develop the criminal case against the man Walker shot, then conducted the department's investigation.

"It would have been nice to have an independent party do the investigation. I would have welcomed it," said Gossage, who retired in 1996 and is now chief of the Hancock, Md., police department.

Walker was assigned to a rapid deployment squad whose dozen members made more than 300 drug and gun arrests a year, police records show.

Placed on routine administrative leave after the March 1993 fatal shooting of an armed 19-year-old drug suspect, Walker and his friend and partner, Officer Dwayne Mitchell, received permission from superiors to continue carrying guns for protection. Mitchell declined to comment for this report.

About midnight on May 18, 1993, Walker and Mitchell met at Walker's apartment. In later statements to police, they acknowledged drinking one beer apiece. Then they set out to get more. On the way, they parked in a crime-ridden section of Marshall Heights.

Nearby stood Nathaniel "Bud" Mitchell, 38, an unemployed sometime panhandler who had served time for robbery in the 1980s. He was carrying a toy gun, and the officers said they saw him threaten his drinking partner, then run as they approached. As the officers chased him up a hill, Bud Mitchell turned and extended the toy gun as if to shoot them, Walker said in a police statement.

Walker and Mitchell fired 23 bullets, striking Bud Mitchell with four, including three from behind.

Still carrying the toy gun, Bud Mitchell fled into a relative's apartment and collapsed on the couch, where he died.

Walker and Mitchell picked up and passed around his toy gun, despite department regulations about preserving evidence, court records show.

Police investigators did not test the officers' blood alcohol levels after the shooting. In a deposition for a lawsuit brought by Mitchell's family, Walker added detail to the account he had given initially to police. He said that Bud Mitchell pointed his toy gun at them while they were in the car. "He walked to the rear of the car, pointed the gun at my head," Walker said. He did not mention this earlier, he said, because "I forgot, I guess."

Walker still patrols the 7th District. A May 1998 lawsuit filed in U.S. District Court said he battered a woman he arrested in Southeast. The woman was charged with assaulting Walker but acquitted. Lawyers for the District have denied wrongdoing on Walker's part.

In a deposition for that lawsuit, Walker said last week that he has been involved in four more shootings since 1994, for a total of 10 during the 1990s, according to attorney Gregory Lattimer, who took the deposition.