The father of a British woman who was last seen entering a New Zealand hotel Saturday made a tearful plea for help Friday - but police said they have "grave fears" about the case.
He added: "Today were have identified and secured a vehicle of interest, and we are now making enquiries to find out exactly where that vehicle has been".
A 26-year-old man, who was with Ms Millane when she was last seen, was speaking with authorities and police advised on Saturday afternoon that he would be charged with her murder.
CCTV footage captured Millane leaving Andy's Burgers & Bar, on the first level of Sky City, at 7.15pm last Saturday, December 1.
Miss Millane's body has not been found, but Det Insp Beard said police were "determined to do everything we can to find her".
He added: "I know that the thoughts of all New Zealanders will be with Grace's family tonight".
Millane was on a year-long OE after graduating from the University of Lincoln in September.
"Of course it's tough, everyone who is a parent out there will understand and appreciate what that family is going through", Beard said.
News of the murder inquiry comes hours after Millane's family said they were "staying very positive" as the search for her continued.
Her father, David Millane, said they last had contact on the day she vanished.
A spokesman for the Foreign Office said: "We are providing consular support to the family in the United Kingdom, and working with the New Zealand Police in relation to reports of a missing British national in New Zealand".
New Zealand Police have announced they believe missing British backpacker Grace Millane, 22, has been murdered.
"We know that he [the 26-year-old man] was with her on the Saturday evening and went to a number of places before going to the CityLife Hotel".
Grace's father today said: "Grace is a lovely, outgoing, fun-loving, family-orientated daughter".
Det Insp Beard said: 'Detectives have assessed Grace's belongings that were found at the backpackers where she was staying.
"She arrived here on the 20th of November, and has been bombarding us with numerous photographs and messages of her adventures", Millane said.
Grace Millane's belongings, including a necklace and a Baby-G watch.
Earlier searches of Ms Millane's accommodation at a backpackers' hostel found several items, including her passport, were missing.
Earlier on Saturday police released images of her necklace and watch and urged anyone who recognised the items to come forward.
He wouldn't speculate where Grace was killed, Beard said.
'We're all extremely upset and it's very hard at this time to describe the range of emotions we are going through'.
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