She was last seen just before dusk on Sunday, September 20, and failed to show up at work at a beekeeping business just 400m from her house the following morning.
This afternoon, Senior Sergeant Peter Payne said police are continuing to ask the public for information that could lead to finding Ewings.
"While we are scaling back the physical search for Melissa, our wider enquiry phase is still ongoing," Payne said.
"Every piece of information we receive helps us build a detailed timeline of her movements."
Ewings had previously lived at accommodation at the beekeeping operation – mainly used by seasonal workers and which includes a caravan - but had moved to her own place about a month ago.
On the day she was last seen, she visited neighbours at around midday.
They told the Herald she appeared "good as gold" and "happy" during the half-hour visit.
An official missing persons search was launched last Monday.
Ewings' house was reportedly found locked, with her car left behind along with her wallet and bank cards. None of her personal belongings were missing.
"Everything was there, nothing had been taken or moved out of the house," her Gold Coast-based grandmother, Dulcie Brumpton said.
Her phone was missing, though.
The Herald understands that police later tracked the phone through cell data to within a 100m radius of her house.
Grid searches were carried out around her property, which includes paddocks with tall grass, State Highway 1, and native bush. Neighbours have also been out trying to find it, and metal detectors have been utilised.
It's not clear if it's yet been found – and police have refused to answer questions about the device.
It's understood that a search team even tried phoning it from a nearby hillside at night to see if it produced any light in the darkness.
CCTV from neighbouring properties have also been seized by police and reviewed for any clues.
Police search teams have gone through all of the local properties and spoken to the residents, the Herald understands, along with Search and Rescue teams scouring the nearby Clarence River which has been swollen and muddy since her disappearance. Coastline checks have also been done, while helicopters have been looking from the skies.
"It's been more than seven days and it's a complete bloody mystery. Something's not right," one local told the Herald.
Detectives from Blenheim CIB are investigating. Police have a mobile base set up nearby and earlier said they have enlisted search teams from all over the South Island to help.
Ewings' employers have not responded to messages.
The family had been told that Ewings had bumped into two elderly women during her walk on Sunday night.
"They said they saw her get in her car and drive home but nobody has seen her since.
"I thought she'd actually walked down... but these ladies said they saw her drive home, so I don't know."
Ewings' mother is said to be distraught and has hardly slept since learning of her disappearance when it was reported by her boss on Monday morning.
"She travels a lot and was working in [Clarence]... and she absolutely loved her job, absolutely loved it. So it's just very strange that all of this has happened," Brumpton said.
Brumpton said she last spoke to her granddaughter on the Friday.
Ewings was in good spirits and was telling her about possible plans to attend a car show on the Saturday with a friend from work.
Brumpton said it was odd for Ewings not to have been in touch with anyone.
"We're starting to wonder a little bit. It's just odd for her not to have been in touch with somebody. She contacts everybody, all the family, all the time."
Ewings' was one of five siblings, she said, and part of a wider tight-knit family.
* Anyone with information is urged to contact 105, quoting file number 200922/5064.