The father of a missing British tourist will be arriving in New Zealand on Friday, as police continue their search.
Grace Millane, 22, was last seen at SkyCity in central Auckland about 7:15pm on Saturday night.
Police haven't ruled out foul play, and are trawling through CCTV footage in the hope of finding a clue as to her whereabouts.
"We have a huge amount of CCTV in the Auckland CBD, and that is our key focus in the investigation at the moment - to work out exactly where Grace went when she left SkyCity on Saturday night," Det Insp Scott Beard told The AM Show on Friday.
"There were people at SkyCity there - we're just trying to establish whether she was actually with anyone in particular."
- Police release CCTV photo of missing UK woman Grace Millane
- Grace Millane disappearance - police give more details
Interviews with her roommates at the hostel didn't go anywhere.
"They're all people doing their OEs and travelling around. We've spoken to them - they can't advance our investigation further."
Police are inquiring with her bank in the UK as to whether her accounts have been accessed, but at this stage it appears not.
The longer this goes on and the more that we don't find her or she doesn't come forward, the more concerning [it becomes]."
Ms Millane had been in New Zealand for two weeks, and Sunday was her 22nd birthday.
Insp Beard says her family will be "pulling their hair out, they'll be distraught".
"If anybody has seen her, or seen her walking around the inner city on Saturday night after 7:15pm, please contact us."
She was wearing a black dress and white shoes, believed to be Converses.
Ms Millane's disappearance has made headlines internationally, with coverage on CNN in the US and all the major news outlets in the UK, such as BBC News, the Daily Mail and Sky News.