John M. Mudd, a Washington liquor store owner who was found guilty in April of receiving a stolen government computer and possessing three unregistered handguns, was placed on probation here yesterday and fined $11,000 by a federal judge who said Mudd had "led an exemplary life" until last year.

Since his conviction by a jury April 30, Mudd has been arrested again and charged with being part of a major nationwide conspiracy to distribute the powerful drug PCP and cocaine.

Yesterday, Assistant U.S. Attorney Barry Tapp said cocaine and marijuana were found in Mudd's Southwest Washington apartment last September at the same time District police discovered the parts of a Wang computer stolen from the U.S. Commerce Department. Tapp said that in another investigation, police found a photograph of Mudd "snorting cocaine in Rio de Janeiro."

U.S. District Court Judge Thomas P. Jackson said he could not take the new charges against Mudd into account when imposing a sentence.

Instead, Jackson said that, according to information provided by probation officers and Mudd's attorney, Gerald Fisher, the 53-year-old Mudd had been "an absolute asset to the community" for 52 years until he was "somehow led astray."

Mudd owns Fair Liquors at 5008 First St. NW, and for years was one of the top-ranked black tennis players in the country.

During Mudd's five-day trial, a string of character witnesses, including David Wilmot, general counsel to the Washington Convention Center and a professor at Georgetown Law School, offered similar praise.

On the witness stand, Mudd acknowledged receiving the Wang computer, worth about $7,000, in six boxes marked "U.S. Department of Commerce." He said he got them at a gas station from a taxi driver to whom he gave $900, but Mudd insisted that he was not aware that the equipment was stolen.

Police said they discovered the computer after they responded to a shooting report and found Mudd in his apartment with a bullet wound in his head. Mudd testified that he had been shot by his girlfriend.

Yesterday Judge Jackson gave probation to the taxi driver, James H. Davis, 37, who also was convicted of possessing the stolen computer.

However, as Mudd was about to leave the courtroom, he was handed an indictment on another charge, possessing a firearm after being convicted of a felony. According to the indictment, police found a pistol in Mudd's apartment on May 31.

Mudd was taken to the Anne Arundel County Jail, where he has been held for the past two months.