One week after leading Montgomery County police to the grave of Michele Dorr, convicted killer Hadden Clark was in Massachusetts yesterday, assisting authorities in a search for more bodies, authorities in Maryland and Massachusetts said.

Yesterday's search, conducted as the first major snowstorm of the season swept across New England, centered on seven wooded acres surrounding a home once owned by Clark's grandparents in the Cape Cod town of Wellfleet. But authorities said dogs trained to sniff out the scent of decaying bodies found nothing before the search was called off about 4 p.m. after six hours.

"He's saying he buried some people out there," a police source said. "He's been hot and cold. Sometimes he's truthful. Sometimes he leads you on a wild-goose chase."

"We are working the case as a serial killing," said a spokesman for the FBI, which is participating in the search.

Sources said that Clark is being investigated in connection with missing person cases in Massachusetts, Connecticut and Pennsylvania.

Clark, 47, who is serving two 30-year sentences--for Michele's slaying and the killing of 23-year-old Laura Houghteling, of Bethesda, has talked generally of burying people in the New England area, where as a youth he spent time with his family, authorities said. They said Clark provided some information about possible victims before leading police to Wellfleet yesterday but gave few specifics.

Philip A. Rollins, district attorney for the Cape Cod area, said detectives from Montgomery County, the Massachusetts State Police and the town of Wellfleet and National Park Service officials were "conducting an investigation" yesterday in Wellfleet, about two hours east of Boston.

"The finding of [Michele's] remains give credibility to his statements," Rollins said at an afternoon news conference.

Police restricted cars on the narrow, winding road leading toward the home.

Police searched the Clark property, which is nestled at the end of a dirt driveway, and the family's burial plot in the Wellfleet cemetery in 1995, according to testimony in Clark's October trial. But the woods surrounding the former Clark property abuts vast acres of federal land that leads to the shore, and police testified that the area was too large to search.

Montgomery County prosecutors argued during Clark's trial last year that he had buried Michele in the family plot, where cadaver-sniffing dogs had indicated human remains had been, and then moved her body after he realized he was the prime suspect in Houghteling's disappearance. But Montgomery police now say Michele's remains lay one to two feet underground in woods adjacent to Route 29 in Silver Spring since shortly after she disappeared in May 1986.

Clark arrived in Massachusetts early yesterday after Chief Judge Cornelius Vaughey, of the Montgomery County District Court, signed an order Wednesday night--based on an affidavit from Montgomery police--for Clark to be released into police custody, according to a source familiar with the investigation.

The order, which is sealed, was then faxed to the Western Correctional Institution in Cumberland, where Montgomery police had been waiting much of the day to begin the drive to Massachusetts, the source said.

About 4 a.m., Clark and another, unidentified prisoner from Maryland were taken to separate, private cells in the Barnstable County jail on Cape Cod, Barnstable sheriff's deputies said.

Montgomery Police Chief Charles A. Moose said yesterday that he sent four homicide detectives, including Lt. Michael Garvey and Detective Edward Tarney, to Massachusetts to help authorities there with a case. He declined to comment further.

FBI agents from Calverton and Boston are also assisting in the Massachusetts investigation, a bureau official said yesterday. The FBI got involved in Clark's case at the request of Montgomery County police, the official said.

Julie Cartwright, a spokeswoman for the National Center for Missing and Exploited Children, said Clark has been investigated previously in connection with three cases of children who vanished.

Information from the Cape Cod Times and Post staff writer David A. Vise was used in this report.

CAPTION: Hadden Clark, shown in 1998, helped officials search for more victims in Massachusetts yesterday.