Prince George's County Executive Jack B. Johnson, who won election in November partly on a campaign theme of reforming the county police force, asked for the resignation yesterday of a former FBI supervisor who was hired to oversee internal police investigations and discipline.

In a letter that police sources said was hand-delivered to Roy Washington, head of the department's Office of Professional Responsibility, Johnson (D) asked him to quit the post to which he was appointed in 2000 by then-Police Chief John S. Farrell. Washington's job was to help root out brutal and corrupt officers and restore confidence in a department tarnished by frequent allegations of wrongdoing.

The move appears to be part of Johnson's effort to put his stamp on the department, which for months has been the focus of a Justice Department civil investigation into charges of systemic misconduct. The letter to Washington was delivered a week after Johnson chose a new police chief for the county: Melvin High, a former top D.C. police official who currently heads the Norfolk department.

If confirmed by the County Council, High will replace Chief Gerald M. Wilson, who took charge of the force last year after Farrell quit.

A spokesman for Johnson said he could not confirm the resignation request because he was unaware of it. Neither Johnson nor Washington responded to a request for comment, and a police department spokesman declined to comment.

Washington was appointed in September 2000, three weeks after an incident in which a county police narcotics investigator in plainclothes followed a man from Hyattsville through the District and into Fairfax County, then fatally shot him in a predawn confrontation.

Cpl. Carlton B. Jones told investigators that he feared for his life when the man he was following, Prince C. Jones Jr., 25, twice backed his car into the officer's vehicle. Fairfax authorities declined to prosecute the officer, who was not related to the man he shot. More than two years later, Prince George's police have not finished their internal probe of the shooting.

Terrell N. Roberts III, a lawyer who has handled numerous misconduct lawsuits against the department, and Redmond Barnes, a member of a citizens group advocating for reform of the police force, said they have not been impressed with Washington.

"I haven't seen any improvement," said Roberts, adding that "there's no integrity in the investigation process" of alleged wrongdoing by officers.

Barnes, of the Peoples' Coalition for Police Accountability, said of Washington: "When they hired him, I thought they were going to get serious about responding to the Justice Department investigation. But Carlton Jones is still in limbo."

As a merit system employee, Washington cannot be fired except for malfeasance, county government sources said yesterday.

They said that if Washington does not resign, Johnson could reassign him to another job in the department. If Johnson attempted to fire Washington by alleging that he is guilty of malfeasance, the source said, Washington could fight Johnson at a hearing.

In a Feb. 13 speech at a banquet sponsored by the Hispanic National Law Enforcement Association and the Professional Black Peace Officers Coalition at a Langley Park restaurant, Johnson said he was counting on the 150 gathered officers to protect the community and uphold constitutional protections against excessive force and unreasonable searches and arrests.

"The reputation we've been living with is not a reputation you created," Johnson said. "It's a new day with new officers who are rooted in the community."

County Executive Jack B. Johnson had a letter delivered to the head of internal investigations.