A flamboyant Virginia lawyer who died in the crash of his small airplane earlier this year was connected in 1978 to one of the largest drug-smuggling rings in Northern Virginia, federal law enforcement investigators said yesterday.

Henry H. Tiffany, a Waynesboro lawyer and land developer who favored white suits and Jaguar cars, was killed on Jan. 9 when his plane was clipped by an Air Force jet off the coast of North Carolina. Investigators had refrained from discussing the circumstances of his death or life until this week, when a major figure in the drug-smuggling ring pleaded guilty.

William Schnepper, a special agent for the Drug Enforcement Administration, said yesterday that Tiffany's final flight was not a subject of his investigation. The agent and other investigators said however, Tiffany was carrying more than a ton of marijuana for the drug ring in 1978 when his plane went down in Haiti with engine trouble.

Tiffany then denied any involvement with drug smuggling, saying he was on his way to Curacao to take aerial photographs of real estate, and Haitian authorities released him after a two-month stay in jail. Schnepper said the smuggling ring had refurbished the landing strip on Tiffany's Virginia farm, given him money to buy an airplane and a prefabricated hangar and promised him about $10,000 to carry the shipment of marijuana from Colombia.

The investigators described Tiffany as "a very minor actor" in a drug-smuggling ring that they said funneled more than 130 tons of marijuana and hashish into the Northern Virginia area during a nine-year period. On Monday federal prosecutors in Alexandria obtained their 21st conviction in the case, when a man they described as a ringleader pleaded guilty to charges of drug racketeering and conspiracy to distribute marijuana and hashish.

Barry Wayne Toombs--known to his colleagues by various aliases, including "Fat Man," "Round Man," "Ice Cream" and "No Corners," according to the agents--was sentenced to 15 years in prison. Only two of the 23 suspects who were charged in the case last year have not pleaded guilty, Schnepper said. One is a fugitive and the other is living outside the country.

Tiffany was not named in the federal indictment. His former administrative assistant in his Waynesboro law office, Lee Berkhimer, said yesterday that Tiffany's former associates would have no comment on the latest assertions.

Tiffany was regarded as a mysterious figure in Waynesboro and Albemarle County where he lived in a closely guarded estate in the foothills of the Blue Ridge mountains. When Haitian police said they had found scores of marijuana bales in and around his disabled plane, the news caused a stir in his home town.

A Haitian judge released Tiffany after concluding that his plane could not hold as many bundles as police said they found at the scene. A federal drug agent said yesterday, however, that the twin-engine craft was big enough. "It could have carried the 2,200 pounds," he said.

The agent said Tiffany would have brought the marijuana to his farm had his plane not been disabled. From there, the agent speculated, the drugs would have been brought by trucks to one of the many "stash houses" the ring rented in Northern Virginia.