The remains of Sarah J. Compton, 66, a Culpeper County, Va., woman who disappeared last summer, have been found in adjacent Madison County, authorities said last night. They said an investigation showed that Compton died of a blow to the head.

Compton, a former Washington area resident who had lived with her husband in Culpeper County for the past eight years, vanished July 5, touching off an intensive search. Her disappearance has been investigated for possible connections to the killings of two other central Virginia women.

As recounted by authorities, Compton left an exercise class in Culpeper about 11:30 a.m. July 5 in her 1988 sedan. A $16 check written about half an hour later indicated that she had stopped at a nearby supermarket.

On July 16, her pocketbook was found in a ditch in Madison County. Her car was found three months later in Henrico County, near Richmond.

On Jan. 24, after the discovery of a human jawbone, investigators began searching near Route 677, about two miles from the town of Madison, and found other skeletal remains, the Madison County Sheriff's Office said.

After an investigation that involved an anthropologist and a dental expert, the state Medical Examiner's Office "reported that the remains were those of Sarah Compton," the sheriff's department said.

Sources familiar with the case said the jawbone apparently was discovered by a dog, which brought it to its owner, who lived nearby.

Representatives of several Virginia law enforcement agencies met July 26 to determine whether Compton's disappearance might be linked to the killing of Nancy Smith Seay, who was found July 23 in Spotsylvania County, and the 1989 killing of an Orange County woman, Ethel Kidd. Officials said the three were of similar height and weight and had similar facial features.