Willie Bullock, described by federal investigators as the key figure in a million-dollar-a-year heroin distribution ring here, was sentenced in U.S. District Court yesterday to serve 10 to 38 years in prison and pay $85,000 in fines.

Federal and local officials said yesterday they believed the sentence inposed by Judge Thomas A. Flannery, which they termed "substantial," would be a warning to other major drug dealers in Washington.

"That type of sentence . . . will serve to place notice on other traffickers out there that they can't be dealing heroin out there on the streets of Washington and get away with it," said David G. Canaday, the special agent in charge of the Washington District office of the Drug Enforcement Administration.

Bullock, 47, who has been known on the street as "Black Willie," pleaded guilty to conspiracy, drug distribution and tax evasion after charges were brought against him in Washington, Maryland and New York.

He was arrested last August after an 18-month investigation. A grand jury indictment that month charged that he supervised seven "street runners" for distribution of heroin in a variety of areas in Northwest Washington, including 14th Street and Wallach Place NW, the 1300 block of T Street and the 900 block of O Street.

Law enforcement officials have said Bullock's activities involved a high grade of heroin that originated from the so-called Golden Crescent area of Afghanistan, Iran and Pakistan. According to investigators, Bullock's suppliers were located in the District, New York, North Carolina, Texas and California.

Bullock, who lives in a custom-built home in Prince George's County, operated a business there that owned and maintained race cars entered in competitions across the country.

His attorney, Benjamin Amos, said yesterday he urged Flannery to consider that Bullock, who also worked as a hairdresser, had been employed even when he was involved in criminal activities and had supported a family, including nine children.

In addition to the prison term imposed yesterday, Flannery ordered that Bullock also serve an extra 10 years on parole, in addition to whatever parole term is set upon his release from prison.

Considering Bullock's age, and the fact that he must serve a minimum of 10 years in jail, that requirement effectively means Bullock would remain on parole for the remainder of his life and be subject to prison again if he violated his parole conditions.

The case against Bullock was handled by officials from the District Police Department and the DEA, operating under a joint narcotics task force. It was supervised by Assistant U.S. Attorney Daniel J. Bernstein.