A science teacher at Fairfax County's Whitman Intermediate School was found fatally stabbed yesterday morning in his Northwest Washington apartment, D.C. police and Fairfax County school officials reported.

Keith Herbert Matthews, 37, a teacher at Whitman for three years, was found lying on the floor of his apartment at 1801 Clydesdale Place NW near Columbia Road in the Lanier Heights section, police said. They said he had been stabbed 19 times in the upper body.

Police said they were called to the scene about 12:30 a.m. by neighbors who said they heard loud noises and screams coming from Matthews' fourth-floor apartment. He was taken to D.C. General Hospital, where he died about five hours later, police said.

Yesterday morning, the principal of Whitman, Eugene U. Jordan, told students of Matthews' death over the public address system and asked for a moment of silence throughout the school, which reopened for the year on Monday.

Matthews, who taught science to eighth graders, was "a quiet, kind of shy type," Jordan told a reporter. "I think the whole building is a little unsettled about this situation."

Carl W. Musser, former principal at the county's Glasgow Intermediate School, said Matthews taught there for about three years before joining the faculty at Whitman.

Police said they know of no motive for the slaying.