Jewellery buried with human remains found on a motorway sliproad near Bristol helped identify them as Melanie Hall who disappeared 13 years ago.
The 25-year-old psychology graduate, from Bradford Leigh, Wiltshire, disappeared in June 1996 after a night out in Bath.
Police showed the jewellery to her parents, Pat and Steve Hall, who have confirmed it was hers.
Mr and Mrs Hall are due to hold a news conference later to help police.
Further tests are being carried out on the remains - found in a bag and buried near a slip road at junction 14 of the M5, north of Bristol, on Monday.
Mr and Mrs Hall are to speak at Bath police station.
Their daughter, who worked as a clerical officer at Bath's Royal United Hospital, was last seen at Cadillacs nightclub in Walcott Street, at about 0100 on 9 June.
Despite a police reward of £10,000 and several appeals on television, no trace of Miss Hall had been found.
A workman clearing vegetation on the slip road off the northbound M5 found a number of bones, including a skull and pelvis.
Other remains were found partially buried nearby.
Forensic science experts sealed off the area on Monday afternoon following the discovery at the exit for Thornbury, in South Gloucestershire.
In 2003, police arrested two men in connection with her disappearance but they were released without charge after police searched buildings and a field near Bath.
At an inquest, Avon coroner Paul Forrest said a lack of evidence meant he would have to record an open verdict, but the circumstances of the case suggested Miss Hall had been unlawfully killed.