Napier schoolgirl Kirsa Jensen disappeared on a horse ride 20 years ago this week, but the file is still open.
Detective Sergeant Brian Schaab, of Napier CIB, says it is rare now for any new information to be added.
Kirsa, a 14-year-old Colenso High School student and daughter of Napier minister Dan Jensen and wife Robyn, went for an after-school ride on the foreshore at Awatoto, just south of Napier, on September 1, 1983.
She was last seen by an old gun emplacement near the mouth of the Tutaekuri River.
Her horse, Commodore, was found tethered by the emplacement, but 20 years on no trace of Kirsa has been found.
A witness, William John Russell, later became a principal suspect and during the investigation he made confessions, which he later re-tracted.
He committed suicide nine years after Kirsa's disappearance.
Mr Schaab, who is in charge of the Kirsa Jensen file, is the officer who oversaw the successful end last year to the 15-year investigation into the murder of 6-year-old Teresa Cormack in 1987.
The Napier detective is still hoping for the right piece of information that will enable him to close the file on Kirsa's disappearance.