Police have reopened their investigation into the disappearance of Auckland girl Joanne Chatfield, almost 20 years since she was last seen.
The 17-year-old south Aucklander went missing after attending a gig at Auckland University on November 19, 1988.
She was last seen walking down Princes Street towards WellesleyStreet, in the central city.
At a media conference this afternoon, police offered a $50,000 reward for information on Miss Chatfield's disappearance. Immunity against prosecution would be considered for anyone who was not the main offender, they said.
Police said they still had no idea of what had happened to the student - who had just finished sixth form - but that after such a long time her disappearance appeared sinister.
Detective Sergeant Len Leleni, from Mangere police, said in spite of extensive inquiries at the time and again over the past 18 months, there had been no sign of her.
He said police had spoken to many people, including school friends, family and colleagues, including some overseas, but no one had been able to provide any helpful information.
Mr Leleni would not say what suburb she lived in at the request of her family.
"She was an intelligent, articulate individual who had aspirations of becoming a journalist. She was well thought of by teachers, students and other close friends.
"She had a zest for life and was excited by the fact that she was moving into a flat in Onehunga."
Mr Leleni said the case was reactivated 18 months ago in an attempt to get closure for police and the family about her fate.
"For the family it is particularly important."
Mr Leleni said none of the clothing she was wearing or belongings she was carrying when she disappeared had been found and her bank account had not been touched.
Police said Miss Chatfield had appeared happy at the time of her last sighting and her family still held a glimmer of hope that she would one day be found.
Anyone with information should contact their nearest police station.
