A D.C. Superior Court jury yesterday convicted three Northwest Washington men in the holdup last December of a Washington gold and silver exchange, leaving both prosecution and defense lawyers puzzled and surprised by the verdict.

The jury of six men and six women deliberated for three days on the unusual case before deciding that the trio -- John McIlwain Jr. of 1300 Columbia Rd. NW, Alvin C. Hines of 832 Rittenhouse St. NW, and Larry T. Lee of 1743 Seaton Pl. NW -- were guilty of armed burglary of the offices of ADE Inc.

Assistant U.S. Attorney F. Joseph Warin had told the jurors the incident was a simple, straightforward robbery, that the men had robbed ADE's owner, Allen Danneman, and an office worker, Lori Greenstein, at gunpoint and emptied a safe of thousands of dollars in jewelry and cash.

Defense lawyers had argued that it was possibly fraud -- but no robbery or burglary. The lawyers said the three men acted in collusion with Danneman and Greenstein and the holdup was part of a scheme concocted by Danneman.

"Crimes have been committed," defense lawyer Stephanie Duncan-Peters conceded. "It could be tax fraud or insurance fraud," she said, but not robbery or burglary.

The focus of the defense was on Greenstein's credibility, since Danneman was not called to testify. Danneman was charged last April with involvement in one of the largest fencing operations in the Washington area, an alleged scheme the FBI investigated under the code name Operation Greenthumb. The charges against him are pending in federal court here. An FBI agent had been working under cover in the store as part of the investigation of Danneman, but the agent was not there at the time of the holdup.

Warin, who called the defense version "preposterous," said the story was concocted by Lee. "What else can he say? He was caught with the goods [jewelry and silver] in his house so he made up the excuse that 'Danneman put us up to it."

Defense lawyers emphasized what they called contradictions in Greenstein's testimony. They argued that she first said $50,000 was taken and then said it was $6,000.

Lawyers on both sides said the verdict appeared to be a compromise. The men were accused of armed robbery of the store, armed robbery of Danneman and Greenstein and armed burglary. The jury found them not guilty of the armed robbery charges, but guilty of armed burglary. None of the lawyers could understand the jury's distinction between the two charges.

"If they were invited in," one defense lawyer said, "then it's neither a robbery or a burglary. If they weren't invited in, then it's both. The decision is completely illogical." Warin also said he was puzzled.