The former gardener at the McLean home of Virginia Lt. Gov. Charles Robb disappeared from his lawyer's office Wednesday moments before his scheduled trial on drug charges in U.S. District Court in Alexandria.

According to U.S. Attorney Henry Hudson, defendant Jean Michel Bardet, 25, asked for the key to the men's room at the office of his lawyer, A. Andrew Giangreco. When Bardet failed to return after several minutes, Giangreco went to the restroom, Hudson said.

The key was there but Bardet had vanished.

A short while later a jury convicted the absent Bardet of possessing 12 ounces of cocaine with intent to distribute it, and of using a telephone to arrange the sale. The maximum combined sentence is 19 years in prison and a $45,000 fine for both counts, court officials said. The maximum for jumping bond is five years' imprisonment.

Bardet and his girl friend, Brenda Kay, had lived at the Robbs' during part of the time Bardet was under investigation, according to drug enforcement officials.

During a bond hearing last month, Kay, who was not charged in the case, was made part of Bardet's release on personal recognizance. But Hudson said yesterday he did not know whether Kay would be held in jail until Bardet returns.

"At this point our major concern is the arrest of Mr. Bardet," he said.

Bardet and Kay had been dismissed by the Robbs several months before Bardet's arrest. An offical said Robb had been unaware of Bardet's drug violation and had cooperated fully with police after he was informed of the investigation.