The body found on a bicycle path in Loudoun County last week was that of Judith L. DeMaria, the 27-year-old woman who disappeared two years ago while jogging, medical authorities said yesterday.

Dr. James Beyer, deputy chief medical examiner in Fairfax County, said the remains discovered Thursday are those of DeMaria, but the cause of death is undetermined.

Police discovered the severely decomposed remains after a man contacted authorities Wednesday with information on the case.

Charles W. Curtis was arrested immediately after the body was found about a mile from the spot where DeMaria was last seen Aug. 2, 1985, while jogging on the Washington & Old Dominion bike path.

Curtis has been charged with murder and is being held without bond at the Loudoun County jail.

According to records filed in Loudoun County General District Court, Curtis admitted to the slaying just before his arrest.

The weapon used was a razor knife, similar to those used for cutting carpets, according to court papers.

Curtis, 28, is a drifter from Martinsburg, W.Va., who most recently was living in his car, according to police. He has lived in Northern Virginia off and on for the past several years, police said.

Authorities said the remains that Curtis led them to were little more than bones and bone fragments. Medical authorities initially had difficulty determining even the sex of the victim, and it was unclear yesterday how the remains eventually were identified.

At the time of her death, DeMaria was a tennis instructor at the Capitol Courts Racquet & Fitness Club in Sterling.