The 26-year-old man who has been speaking with police about the disappearance of British backpacker Grace Millane will be charged with her murder.
Auckland City Police Detective Inspector Scott Beard said evidence they had located so far told them Grace was "no longer alive".
"I know that the thoughts of all New Zealanders will be with Grace's family tonight and I want to reassure everyone both here and overseas, that NZ Police are determined to do everything we can to find Grace", Beard added.
Grace Millane, 22, from Essex in the United Kingdom, was last seen in central Auckland on December 1 and was reported missing on Wednesday.
Beard said police questioned the man seen with her that night and have named him as a person of interest - but he has not been taken into custody.
This morning police released photos of a necklace and pink Casio Baby-G watch Millane was thought to be wearing when she disappeared, and said her passport was also missing.
He added: "I know that the thoughts of all New Zealanders will be with Grace's family tonight".
She had booked to stay at the Base Backpackers hostel in central Auckland until 8 December.
"Her family are devastated", he said.
News of the murder inquiry comes hours after Millane's family said they were "staying very positive" as the search for her continued.
Millane's father David, a millionaire property developer, flew into New Zealand early yesterday.
He tearfully explained that his daughter has never been out of contact with her family for such a long period of time, usually contacting them on social media.
That was especially so for David Millane, as police had met the distraught father, but also for other family in the United Kingdom, including Millane's mother Gillian, unable to travel to New Zealand because she was recovering from an operation.
"We still do not know where Grace is", Detective Inspector Beard said.
The charge comes after police confirmed Millane's disappearance was being treated as a homicide, at a press conference this afternoon.
"We know that he was with her on the Saturday evening and went to a number of places before going to the Citylife Hotel", he told reporters.
"The issue here is Grace is still missing and we want to find her".
Asked if they had met on the Tinder dating app, the detective said: "I'm not going to speculate on how they met". "We are all extremely upset, and it's very hard at this time to fully describe the range of emotions we are going through".
'Grace is a lovely, outgoing, fun-loving and family orientated daughter'.
Police said they had received dozens of calls to a hotline and more than 25 staff were working on the case, trawling through hours of CCTV footage to trace her movements.