What happened to Shirley Warrington?
It's been the question on so many minds in Christchurch this week - her family, police, the community.
How can an 85-year-old woman simply disappear into the dark night?
Where is she? How has there been no sign of her?
And why was the search for her called off after just two days?
Senior journalist Anna Leask spoke to the head of the investigation about the mysterious and sad case.
There was nothing strange about Shirley and Wally Warrington's decision to go for a drive on Saturday night.
But what happened to them after they left their Burwood home would inhabit headlines across the country for days.
The theories around Shirley's vanishing have been rampant this week and mostly unhelpful.
She and Wally were happily married, neither in the best health but both dedicated to living their best lives together.
When they went for that fateful drive though, that life was shattered.
Three things are very clear.
At 7.30pm the Warringtons were stopped at Rolleston by police, driving slowly on State Highway 1 towards Christchurch with their headlights on full beam, and well under the speed limit.
They were doing nothing wrong, but the police would have been remiss not to pull them over in the circumstances.
After a quick chat, the Warringtons were back on the road.
At 8.34pm their car was captured on CCTV camera on Ferry Rd - Wally driving and Shirley in the front passenger seat.
At 10.19pm another camera picked the car up near the Ferrymead Bridge.
This time, there was no Shirley.
Detective Senior Sergeant Damon Wells wanted to be clear - very - about one thing.
"There is absolutely no indication Wally's involved in doing something sinister," he stated.
"Quite the opposite, in fact - he was a doting husband.
"Shirley has wanted to go for a walk and while he's been waiting for her to get back he's fallen asleep.
"When he woke up she wasn't back… he's guilt-stricken."
Wally, whose health is faltering, left the area, desperate to find help and raise the alarm.
His memory is not the best, and while he was confused about the chain of events that night he was able to describe "rope fences" and "old buildings" to police.
That led them to Ferrymead.
Between that location and the CCTV footage of the couple's vehicle, Wells said police and Land Search and Rescue experts were able to dictate a boundary for the hunt for Shirley.
They considered the weather and the surrounds and spoke to survival experts about how far Shirley - based on her physical health and fitness, early stage dementia and the light clothing she was wearing - could have walked and how long she could exist out in the cold Canterbury nights.
Temperatures plunged to well below zero, -5C at one point, and Shirley was only in light clothing.
Wells said even he - a fit and able cop - would likely not have survived a night out there.
More than 40 people and dogs - police dogs, search dogs and some that have worked both disciplines - combed Ferrymead, the surrounding areas, bush tracks, waterways.
They used a high-tech Fire and Emergency New Zealand drone to fly above the search area, it's infra-red and heat seeking capacity trained on the cold earth looking for any sign of the missing pensioner.
"We flew the drone up over Whitewash Head and Godley Head too, just in case," said Wells.
"We deferred to the experts in cases like this, this is their bread and butter… we can't go out and search the whole of Christchurch - that's not even remotely possible.
"We searched everywhere within the boundary - sheds, backyards, railways, riverbeds… the estuary, the ponds... and anywhere a person could curl up.
"There's no indication she's walked into the river, it's very muddy and there we would see footprints if that was the case."
Wells considered bringing in the police dive team but the search did not warrant it.
The water in the area Shirley was last seen is mostly shallow and she would have been visible had she fallen in.
If she fell from the Ferrymead Bridge she may have been carried to the estuary or the ocean and Wells said it was impossible to pinpoint a search area in that scenario.
After two days the physical search was suspended.
That decision was explained to Shirley's family in full before police announced it to the public.
They understood that everything that could have been done to that point, had been.
Suspended does not mean called off. And it does not mean police have stopped looking.
It means the full-scale search has stopped.
Police are still investigating and all information is being assessed and followed up.
Any sign or sighting that is credible, Wells will deploy his team again.
Behind the scenes police carried out a forensic examination of the Warrington's car - a standard task in a missing person inquiry - to ensure there was no evidence of foul play.
They also considered that Shirley may have been picked up by someone else and harmed.
Police have saved screeds of footage from their own CCTV cameras, traffic cameras, private cameras and those on digital billboards around the search area.
They will be looked at in detail if and when needed.
"We have all the footage saved and if something untoward has happened we will go back and look," Wells said.
"There were hundreds of cars floating around that night, it was Matariki and there were cars galore… logistically, if we spoke to everyone of those people it would take years.
"And if there is something untoward, absolutely we will do that - but for now there's nothing to suggest that."
Wells, a senior and experienced police officer, said searches for missing people had to be based on "best options".
His team had faced a barrage of criticism - mostly on social media by the public - around his decision to suspend the search.
He stands by it and while he's vowing to do everything in his power to find Shirley he makes no apologies for making hard and realistic calls.
"Do we go and talk to people just for the sake of it without any indication of foul play?
"Say we pulled 50 staff onto this for the next two weeks - they wouldn't be doing road policing or investigating burglaries or child abuse or gang tensions…. We can't have every police officer on every job, it's about finding the balance."
Wells met with Shirley's family personally and talked them through that, saying they understood and respected the process.
They had continued to look for her which Wells said was "awesome" and he was making sure his team followed up every piece of information that came in.
"We met with the family and answered all their questions, it's important that they know we actually care," he said.
"This is about them. We don't like the fact that we haven't returned a person to her family, or their body so at least they can have some closure - that's the end goal."
Wells appealed to Christchurch residents to keep an eye out for Shirley in the coming weeks.
School holidays meant some people may not have been home when she vanished and he asked them to check their properties when they returned.
"If you're going walking up the Bridle Path and in the hills maybe keep an eye off the side of the tracks, check behind bushes… if a rock climber is up around the rocks she may have crawled in underneath one.
"It's the public who are going to find her - not us."
Wells said nothing had been ruled out but at this stage it was likely Shirley had gotten lost or hurt out in the dark and cold, and died.
He hoped he was wrong.
But his training, experience, history and science made him sadly pragmatic.
"It sucks because we can't find her at this stage… but it ain't over yet," he said.
CAN YOU HELP POLICE FIND SHIRLEY WARRINGTON
Anyone with information that may help locate Shirley is asked to call 111 and quote file number 210711/8724.