Police investigating the homicide of Auckland teen Jane Furlong are offering a $50,000 reward to help solve her 1993 murder.
Police revealed details of the reward offer at a press conference in Auckland this afternoon.
Police have also confirmed that Ms Furlong's partner Danny Norsworthy is refusing to speak to investigators.
Investigators say a number of people - including Mr Norsworthy - were refusing to talk to police and the reward was designed to be an incentive to talk.
"The investigation team continues to work tirelessly on this mystery and has done so ever since the remains were confirmed as Jane's. This announcement is just another phase in the operation,'' said Detective inspector Mark Benefield, officer in charge of the homicide investigation.
"We have interviewed and spoken with literally hundreds of people, some of whom have been less helpful than others. Our investigations have taken us far and wide and may continue to do so.
"We know there are people who know what happened to Jane after she was reportedly last seen on May 26, 1993 and those people owe it to themselves, Jane's memory, her family and friends to tell us what they know.''
It was not clear when she died or when she was buried at Port Waikato but police believed it was possible she may have been alive for at least a few days after she was reportedly last seen.
"Our overriding objectives have always been to establish - as best we can - when, where, how and at whose hands Jane died and how she ended up buried at Port Waikato,'' Mr Benefield said.
"We believe more than one person was involved or at least has vital information about her disappearance and death.''
A large billboard advising of the $50,000 reward offer would be installed this afternoon at the western end of Karangahape Rd.
Ms Furlong's body was found on May 19 last year, buried deep in sand dunes at a south Auckland beach, 19 years after she was last seen alive.
Ms Furlong, then just 17, disappeared from Karangahape Rd in the central city in May 1993. Her remains were found in a sandy grave at Sunset Beach near Port Waikato. Police believe she was murdered and continue to hunt for her killer.
She had given birth to her son Aidan just months before she vanished.