A two year police investigation into the 1993 disappearance and murder of Jane Furlong has wound down without result.
Seventeen-year-old Furlong's remains were unexpectedly discovered at Port Waikato's Sunset beach in May 2012.
Since then police staff have spent thousands of hours on the homicide investigation, Operation Darlia.
Furlong, a part-time sex worker, was last seen by her boyfriend after he had dropped her off to work on Auckland's Karangahape Rd on May 28, 1993.
Detective Inspector Mark Benefield said the file would stay open but the murder would no longer be actively investigated unless there was new information.
"We have explored hundreds of theories and a number of leads and I am confident that, if we get the right information from the right people in due course, we will be able to tell Jane's family who was responsible."
Mother Judith Furlong said she was appreciative of police efforts.
She had previously told media, she had a 'very strong idea' who killed her daughter.
Anyone with information can call 0800675263, the line will be kept open for a few more weeks, police said.