Police have not been able to locate a Somerville man who, after being convicted Monday of raping a Harvard student last February, disappeared from the court before he could be sentenced.

Twenty-eight year-old William G. Morrissey walked out of the Middlesex County Superior Court around 4:15 p.m. while a jury of ten men and two women were deliberating charges of rape and kidnapping against him, David M. Siegel, assistant district attorney for Middlesex County said yesterday. Morrissey told Paul A. D'Agostino, his attorney, that he was going to get a cup of coffee, Siegel said.

After a search of the building failed to recover Morrissey, Judge Alan J. Dimond received the jury's verdict convicting Morrissey of raping a Dunster House senior February 27 on Sparks St. near the Loeb Drama Center, Siegel said.

"We've contacted every possible law enforcement agency that might come in contact with him, including the five local and state police, the U.S. Border Patrol, the Customs Service, and Canadian officials," Siegel said.

Lawerence Gilligan, special agent in the Boston office of the Federal Bureau of Investigation, said yesterday his office is not currently involved in the matter, but could search for Morrissey on charges of unlawful flight to avoid prosecution or confinement. "The District Attorney would need information and evidence that Morrissey had fled across state lines and agree to pay extradition costs before the FBI would get involved," Gilligan said.

Siegel said testimony at Morrissey's arraignment September 24 stated that he' had previous felony convictions and that he had fled to Canada after being indicted for rape in another incident.

On September 1, a Cambridge police officer allegedly saw Morrissey chase a woman through the same intersection of Brattle St. and Sparks St. where the Harvard student was raped. A composite drawing of Morrissey was shown to the Harvard victim, and she identified him as her assailant, Siegel said.

Siegel said Morrissey, who was free prior to the trial on $1000 cash bail, is 5'7" tall, slim with brown hair, and "he is known to frequent the Harvard Square area," Siegel added.