New Hampshire police yesterday confirmed that a female amnesia victim found last week is not Joan L. Webster, a Graduate School of Design student missing since November.

Lt. Richard Tuck said that a comparison of dental records indicated that the still-unidentified woman picked up in Pinkham Notch, N.H. is not Webster.

Police officials also said that a decapitated female body, found in Lowell. Mass, and examined in the Webster case, had been identified as a local woman.

Poor weather yesterday hampered the search of Walden Pond in Concord, Mass, where area police began drugging the pond bottom Friday to locate the graduate student's body.

Middlesex District Attorney John Droney received an anonymous letter last week stating that Webster's body had been placed in a bag and dumped in the pond.

Police divers combed the pond bottom over the weekend, without finding clues.

Webster was last seen November 28 in the baggage claim area of Eastern Airlines at Logan Airport. She was returning to Cambridge after spending the Thanksgiving holidays with her family in New Jersey.