Robert B. Reckmeyer, suspected of being a "kingpin" of an alleged nationwide drug ring based in Loudoun County, and nine other persons arrested last week on conspiracy charges in connection with the case pleaded not guilty yesterday in U.S. District Court in Alexandria.

Judge Albert V. Bryan Jr. set March 18 as the trial date for the 10 defendants, who allegedly conspired to distribute 293 tons of marijuana and hashish over the last decade.

"The roles assumed by these defendants were interchangeable at various times throughout the conspiracy," said Assistant U.S. Attorney Karen P. Tandy. According to the indictment those roles included, "financier, organizer, manager, truck driver, distributor, stash house sitter and currency courier."

The hashish was imported from Lebanon and the marijuana from Colombia and Mexico, according to prosecutors. After being brought ashore in boats along the East Coast, the drugs were stored in various Washington area warehouses and then distributed, they said.

A secluded 1,000-acre Loudoun County estate, Shelburne Glebe Farm, was allegedly the headquarters of the operation, which the indictment said had grossed more than $100 million since 1974. Last week federal and state investigators said they seized the estate and discovered $200,000 in cash, 35 pounds of silver dollars, and false birth certificates there.

Divers from the Virginia State Police also began searching the estate's private lake for precious gems and other valuables that were allegedly used to mask profits earned from drug sales, but the bitterly cold weather has stalled that search, police said.

As many as 120 federal and state agents are working on the case. Though 10 arrests have been made, they said they are still searching for 16 additional persons charged in the indictment. Among those still at large are Christopher F. Reckmeyer, the owner of the Shelburne Glebe Farm and Bruce W. Thomason of Waldorf, Md.

The Reckmeyer brothers and Thomason were allegedly the "kingpins," masterminding the criminal enterprise, Tandy said. If convicted of directing the alleged drug ring, she said they could be sentenced to up to life imprisonment without the possibility of parole under tougher federal drug trafficking laws, effective Jan. 1 of this year.

Robert Reckmeyer, 30, charged with 24 counts of drug, firearms and tax violations, will be detained in the D.C. Jail without bond until the trial.

A federal judge ruled on Friday that there was a "high risk" that Reckmeyer would flee if he were released on bond.

Reckmeyer's wife, Patricia, indicted on one drug charge and five tax violations, was released last week on personal bond to nurse her month-old baby. The other eight defendants posted their bonds and were released pending the outcome of the jury trial.