A Prince George's County Circuit Court jury convicted a Baltimore woman of second-degree murder last night in the death of her boyfriend, a member of the Marine Corps Band.

The jurors returned their verdict against Brigette D. Woodbury, 19, after deliberating 6 1/2 hours. Woodbury could be sentenced to up to 30 years in prison for the crime, defined as intentional killing with malice but without premeditation. Judge David Gray Ross ordered a presentence report and continued the case until June 10.

Woodbury told the jury that Paul A. French, a 42-year-old clarinetist, was waving a knife at her during an argument and she grabbed it away from him and stabbed him with it. The stabbing occurred last Aug. 5 in the bedroom of the apartment they shared in Oxon Hill.

Police testified they found blood-soaked bedsheets, and Assistant State's Attorney William Missouri argued that this suggested that Woodbury had intentionally attacked French while he slept.

Woodbury's attorney, Elvira White, argued that her client had acted in "imperfect self-defense," meaning that she believed at the time that she was in danger, even though most "reasonable" people would not think so.

White also said Woodbury has a history of emotional problems, documented by a psychiatrist who examined her. On several occasions during the trial, Woodbury suddenly announced she was hearing voices.

According to county police, Woodbury checked herself into the Walter P. Carter Center after the slaying. The center is a state mental hospital in Baltimore where Woodbury previously had been a patient. Police were not allowed to question her for several weeks. She was arrested and charged with first-degree murder on Aug. 23.

Attorneys in the case said French had a top security clearance because he often performed at the White House.

He met Woodbury at the Tic Toc Club in Baltimore, where she was a striptease dancer, according to testimony. Friends of both Woodbury and French testified that the couple had lived together for aboout seven months before French was killed.