Police say the disappearance of 22-year-old British backpacker Grace Millane is being treated as a homicide, and a 26-year-old man is speaking to police.

Millane, who was last seen on December 1, travelled to New Zealand as part of a gap year.

Detective Inspector Scott Beard said police found a man at an address just after 3pm today and a vehicle of interest was also found.

"We still don't know where Grace is," Beard said, who added police have identified a vehicle of interest today.

"Her family are devastated," he said.

"I want to reassure the public police are determined to do everything we can to find her.

"The man is the same one who was named as a person of interest yesterday."

The last confirmed sighting of Grace is still 9.41pm Saturday night going into the CityLife Hotel, Beard said.

The man was with her on Saturday evening, but Beard didn't know if the pair knew each other before then.

He wouldn't speculate on how they met.

"The issue here is Grace is still missing and we want to find her."

Evidence they had found had indicated Grace was no longer alive, Beard said.

"We don't know what's happened to the property of hers that has been missing," he said.

He wouldn't speculate where Grace was killed.

"It's a combination of our total investigation, including forensic investigation," he said about how they had come to believe Grace had been murdered.

Beard said police had no idea what the motive was.

"Of course it's tough, everybody who is a parent out there will appreciate and understand what they're going through," Beard said of Grace's family.

Items of interest

Earlier today police investigating Millane's disappearance released photographs of jewellery that is missing from the backpackers where she was staying.

More than two dozen police officers have been investigating the 22-year-old's disappearance since she was reported missing earlier this week.

They revealed on Friday that their investigations included questioning the man who was with Millane when she was last seen.

CCTV cameras captured Millane at the CityLife Hotel on Queen St at 9.41pm on December 1.

Police have said they have assessed Millane's property left at the backpackers where she was staying - and found some items missing.

Her passport, a pale pink Casio Baby-G watch and necklace have not been found.

Police believe Millane may have the items with her.

The necklace is described as silver and round with a green stone in the middle of it.

Grace's passport, a pale pink Casio Baby-G watch and necklace have not been found. Photos / Supplied

Police would like to hear from anyone who has seen any items matching this description over the past week.

Detective Inspector Scott Beard said a scene examination at the hotel is continuing and investigators were progressing with the viewing of hundreds of hours of CCTV footage.

"At this point our enquiries have not led us to any further confirmed sightings of Grace, and the last known sighting is of her entering the Citylife Hotel," he said.

"Dozens of calls have been made to the 0800 number and all of this information continues to be reviewed and assessed.

"Many of these calls have been from members of the public, offering accommodation and assistance to the Millane family."

Police continue to offer support to the Millane family, both in New Zealand and in the UK.

On Friday, Millane's father, David Millane, flew into the country.

At a press conference that afternoon, fighting back tears, he struggled to speak as he described his "lovely, outgoing, fun-loving, family-oriented daughter".

"Grace has never been out of contact for this long. She's usually in daily contact with her mother, myself, her two brothers ... and on social media."

His daughter had started her year-long OE in Peru and had told her family how much she was looking forward to moving on to New Zealand.
"She'd been bombarding us with numerous photos and messages of her adventures. We're all extremely upset and it's difficult to describe the wave of emotions we're going through."

He appealed for people with information to contact police - no detail was too small, Millane said.

The millionaire property developer was last in contact with his daughter on Saturday. Anyone with information about the missing items can contact 0800 676 255.