An avid mountaineer who earlier survived eight days stranded high in the Southern Alps is missing again.
Marni Sheppeard was last heard from in Christchurch about 5.20am on November 19 before being reported missing last month.
Police were now calling for help from the public to locate the 53-year-old, who holds a PhD in theoretical physics.
She earlier posted a photo of herself to Twitter titled "off to the mountains", with police establishing she later took a bus west of Christchurch.
Her last recorded bank transaction was about 8.30am on November 19 at the Darfield Fruit and Vegetable Store in the small town of Darfield.
Sheppeard had extensive mountain experience, police said.
Not only has she summited Aoraki Mt Cook, but she also joined Wanaka's search and rescue team where she trained for alpine operations.
She had also survived being on the other end of search and rescue missions.
That included being rescued from a crevasse in the Swiss Alps after injuring her ankle.
And - later in 2003 - surviving eight days after being stranded with a fellow physics student on an exposed ridge in Arthurs Pass National Park.
Police said Sheppeard was known to frequent the Arthurs Pass and West Coast areas.
She is described as being about 1.62m tall and of slim build.
She was last seen wearing a black T-shirt and carrying a green Macpac backpack.
"Police are concerned for Marni's safety and wellbeing and are working on a few narrow leads into her possible whereabouts."
They appealed to anyone who may have spoken with or seen Marni Sheppeard since November 19 to contact them on police helpline 105, quoting file number 210115/4277.