A Falls Church man was charged with murder yesterday in the decapitation of one of his roommates, Falls Church police said.

William S. Bly, 29, of 619 Laura Dr., allegedly slashed the throat of Daniel J. McAllister, 36, and then chopped off his head at their house Wednesday night, according to Police Chief S. Kenneth Johnson.

Police said yesterday they were unsure what was used in the decapitation. Johnson said a broken glass ash tray, broken window glass and a knife were found at the scene.

Fairfax General District Court Judge Robert M. Hurst ordered a psychiatric examination for Bly.

A third roommate at the apartment, James Tong, 36, arrived home about 5:30 p.m. Wednesday and found the Bly had locked him out, police said. Tong telephoned police to report a domestic disturbance.

Police said Bly let them into the house where they found the decapitated body lying inside the bedroom doorway. McAllister had also been stabbed and cut several times in the neck and upper chest, police said.

Lt. Greg King, the investigating officer, said Bly's hands were cut and he was treated by medics at the police station, then was taken to the county jail.

Bly and McAllister had been employed at nearby National Memorial Cemetery, King said, but Bly was fired several weeks ago.

Bly moved into the one-story brick house on the quiet residential street about four months ago. The other men had lived there longer, police said.