Police say they have no evidence of foul play in the case of missing Alexandra woman Denise Potter but they have not ruled it out.
The 53-year-old disappeared at about midday on Sunday from the garden at her daughter's Dunedin home.
A police spokesperson said the disappearance was out of character and police were not aware of any health issues that would prompt Ms Potter to wander off.
He said they saw no link between her disappearance and a TVNZ programme about Ms Potter and her husband Steve Potter's campaign against the wrongful conviction of Shane Gribb, which aired this week.
Mr Potter and his 25-year-old daughter Sharelle spoke to media outside the Dunedin Police Station this afternoon.
Mr Potter told the news conference the family did not think she would have ventured far, because she was tired and not wearing shoes.
He urged people to check garden sheds and any location where a person may get stuck and not be able to call for help.
He said the family had been humbled by support received from the community and said many people were helping with the search.
The Otago Coastal Area Commander, Inspector Jason Guthrie, asked residents to check their properties for any sign of Ms Potter
"At this stage, there's nothing to suggest foul play. The most important thing for us is a sighting, and in the absence of a confirmed sighting, it's fairly difficult to progress the inquiry," he said.
"There are a range of inquiries that we can do around the use of bank cards and that type of thing. We've exhausted all of those lines of inquiry."
Inspector Guthrie said police were keeping an open mind about the possibility of foul play.
He said there had been no confirmed sightings since Ms Potter went missing and anyone with information about her should contact Dunedin Police.
Advice for volunteers
Police have urged the large number of volunteers looking for Ms Potter to stay safe while they do so.
Detective Hayden Smale and Ms Potter's husband, Steve, said people needed to stay in groups and keep safe as they searched for her.
They said there had been vast support for the family since she went missing.
Police have asked members of the public who think they may have seen Ms Potter to contact Dunedin Police rather than posting possible sightings on Facebook.
Ms Potter was last seen wearing dark blue jeans and a black and grey long-sleeved shirt, and had bare feet.
Police have grave concerns for her safety.