A man will be charged with the murder of British backpacker Grace Millane in New Zealand.
The 26-year-old man has been speaking with police in Auckland in relation to her disappearance, officers said.
Ms Millane, 22, was last seen in the city on December 1.
Her family have been left “devastated” by the development, Auckland City Police Detective Inspector Scott Beard said.
“The evidence we have located so far, our scene examination, some of the CCTV footage we have, and our investigation, has determined that Grace is no longer alive and that this is a murder investigation,” he told a press conference.
“Grace’s family have been advised of this development and they are devastated.”
Det Insp Beard added: “We still do not know where Grace is. We are determined to find her and return her to her family.”
Ms Millane, from Essex, was described as a “lovely, outgoing, fun-loving, family-orientated daughter” by her father, David Millane.
She graduated from the University of Lincoln in September and had embarked on a year-long worldwide trip.
After visiting Peru she arrived in New Zealand on November 20 and had been near-daily contact with her family until December 1 – the day before her 22nd birthday.
The last confirmed sighting of Ms Millane was at 9.41pm the same day at the Citylife Hotel in central Auckland, when she was seen with a “male companion”.
Police later said they had spoken to the man and that he was a “person of interest”, although he was not held in custody.
Det Insp Beard confirmed that the man being questioned by police on Saturday was the same individual.
“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.
Police have not uncovered any evidence the pair had met before. Asked if they had met on the Tinder dating app, the detective said: “I’m not going to speculate on how they met. The issue here is Grace is still missing and we want to find her.”
Detectives seized a “vehicle of interest” on Saturday and inquiries were under way to establish where it had been.