The Maryland Court of Special Appeals has ordered a new trial for a Prince George's man convicted of murdering an off-duty police officer and a Vietnamese refugee store manager at the Greenbelt Mini-Mart in June 1983.

In its ruling yesterday, the state's second highest court said it was overturning the conviction of Kamel Ali Elfadl because police detectives refused to allow him to see a lawyer until after he had signed a confession.

Elfadl, 22, a Lebanese national who was attending Prince George's County Community College, and his former roommate, Kenneth Lodowski, were convicted in separate trials of robbing and murdering Prince George's police officer Carlton X. Fletcher and Minh Phamdo as the two men were about to deposit the day's receipts.

Elfadl, who formerly worked at the store, was sentenced to six consecutive life sentences for the robbery and murders. Lodowski, who was sentenced to death, has appealed his conviction.

Assistant Attorney General Richard Rosenblatt, who argued the case before the appellate court, and prosecutor William Missouri, who assisted in the original trial with Prince George's State's Attorney Arthur A. Marshall, both expressed surprise at the appellate decision.

Missouri and Rosenblatt said they had expected the court to find the use of the written confession a "harmless error" that played no part in the outcome of the trial because Elfadl also had given police a detailed oral confession.

During the trial last winter in Calvert County, Elfadl's attorneys objected to the inclusion of the written confession, which they said violated his constitutional rights because it was obtained after police allegedly threatened him and refused to allow him to see a lawyer hired by his wife.

Trial Judge Jacob A. Levin denied the motion by Elfadl's lawyers to suppress the written statement.

But Rosenblatt argued that even without the written statement, the oral confession, given to police before the lawyer arrived at the police station, should be admissible in court. The appeals court let the oral statement stand.

Rosenblatt, who is scheduled to argue the Lodowski appeal today before the Court of Appeals, said he will probably ask the court, the state's highest, to consider the Elfadl case as well.

While the Court of Special Appeals praised the police for apprehending the suspects, Judge James S. Getty wrote on behalf of the panel, "The method employed in gathering evidence must conform to constitutional guarantees."

Added Getty, "We do not lightly reverse a conviction for the brutal, senseless assassination of two citizens, one of whom was a police officer."