The family of a student who vanished without trace 12 years ago have told of their daily pain at not knowing her fate.

Elizabeth Chau's parents refuse to move house or change their phone number in the hope she might return, and have endured the anguish of repeated false sightings.

The family spoke as Scotland Yard offered a £15,000 reward for information that helps solve the mystery of Elizabeth's disappearance and that of another young woman, Lola Shenkoya, nine months later.

Detectives questioned serial rapist Andrezej Kunowski, who has since died, about both girls but no concrete evidence was found linking him to their disappearances.

Elizabeth, then 19, was last seen a mile from her Ealing home after handing in an assignment at Thames Valley University in April 1999.

This week her parents were once again handing out leaflets with a fresh appeal to find her.

Her brother Minh Chau, 38, said her disappearance had left the family "devastated" and they needed to know her fate.

He said: "We have no closure and live with the pain every day. My parents are particularly distraught. They have not changed their phone number or moved house in the hope that she may one day return.

"My mother sees her in the street constantly and when she finds out that it's not her she gets very emotional.

"Having a loved one go missing is about the worst thing that can happen. We are always thinking of her and can't move on."

Mr Chau said it was "baffling" no one had seen what happened to her after she was filmed on CCTV walking past Ealing police station at 6pm on 16 April. He said: "When she didn't come home that night we were immediately worried. She was a very responsible girl and would always contact us if she was going to be late.

"She was a very considerate and caring young lady, an angel really. She didn't go out that much and was dedicated to her studies."

Computer graduate Ms Shenkoya, then 27, vanished from the same area on 3 January 2000.

Detective Chief Inspector Lee Presland, of the Met's Homicide and Serious Crime Command, said: "We are hoping that some information on either of the girls comes forward. We desperately want to provide some closure to the families. Maybe 12 years later someone will provide information that they didn't at the time, maybe their allegiances have changed and they feel they can do so now."

Kunowski, dubbed "The Beast", died in jail after he raped a student and he was linked through DNA to the murder of 12-year-old Katerina Koneva in her west London home in 1997. He had also committed at least 17 rapes in his native Poland.

Mr Presland said officers quizzed Kunowski about Elizabeth and Lola "because they are both young girls who went missing in the area he operated in. We were just never able to find any evidence to connect him".

Anyone with information should call police on 020 8358 0300.