The sister of a woman who went missing while fruit-picking in southern NSW 18 years ago says her family has endured "ambiguous loss" ever since.
Niamh Maye, then 18, left a Jingellic campground on March 30, 2002 but failed to travel from Batlow to Sydney in time for Easter as previously arranged.
She has never been found and no one has been charged over her disappearance, but a 2012 coronial inquest found she had died at or near Tumut on March 30 or 31.
Fionnuala Hagerty, one of Ms Maye's six siblings, told reporters on Sunday that Ms Maye had been driven from Jingellic to Tumut by a fellow fruit-picker who died some six months afterwards. He was the last person known to have seen her alive.
Ms Hagerty said her family deals with constant ambiguity over Ms Maye's fate and her parents had spent years travelling from Armidale to Tumut to help look for their daughter.
"Just when you think you've come to turns with a potential reality ... more information might come in and then more questions come up," she said.
"Some people call it ambiguous loss.
"The rational part of your brain knows what's happened but the emotional part of you doesn't want that to be the reality and because you don't have the answers, there are still possibilities."
NSW Police on Sunday renewed their appeal for information on Ms Maye's disappearance as this year's Missing Persons Week kicks off, and said in a statement the case was being reviewed under the unsolved homicide framework.
The police force in July last year established a Missing Persons Registry made up of seven detectives and four analysts dedicated to long-standing missing persons case and assisting frontline officers with immediate missing persons cases.
Some 57 long-term missing people have been located to date by the registry, while 99 per cent of people who have gone missing in 2020 have been located within 90 days.
"To have a loved one go missing has a devastating impact on family, friends and the wider community and while police do an outstanding job in providing support for the families, we are also committed to providing answers," NSW Police Commissioner Mick Fuller said.