Mandeep Srawn admits she is blinded by a sister's love.

On Monday, May 13, her brother Prabhdeep, walked into rugged mountain terrain near the highest peaks on the Australian mainland.

He hasn't been seen since, but Mandeep won't leave until he is found.

The 25-year-old Canadian law student was last seen parking his rented vehicle at Charlotte Pass, and setting off towards the Main Range Walking Track in Kosciuszko National Park, wearing a white T-shirt and blue jeans, and possibly carrying a light ski jacket.

The trek from Charlotte Pass along the Main Range walk winds through alpine country above the tree line, cutting between and climbing over the rough peaks of the Snowy Mountains.

On the morning Prabh set off, it was a fine, mild day - temperatures were above zero, and the walking track was clear.

But late in the afternoon a cold front moved through, with the resulting blizzard dumping centimetres of snow, covering the paths. He didn't make it back to his car that night.

The alarm was raised a week later.

Prabh's family in Canada received the call in the early hours of a Sunday, and by the afternoon his sister Mandeep and parents Major and Devinder were on a flight from Toronto to the small lakeside town of Jindabyne in New South Wales' Snowy Mountains.

They were joined by his cousin, Rajveer.

Not much is known about how well-prepared Prabh was. When Mandeep found her brother's laptop, a search revealed his likely route was towards Mount Townsend, Australia's second-highest peak, north-west of Mount Kosciuszko and a short distance off the Main Range walk.

A Canadian army reservist of six years, Prabh used to lecture on survival skills.

Mandeep and Rajveer found dozens of pages of notes on "winter warfare" filed on his computer, with evidence of planning for the hike in the search history.

But police don't know what supplies Prabh took with him for a trek which is usually just a day trip.

Hikers experienced in the sometimes unforgiving landscape of Kosciuszko have seen best and worst practice emerge in daily news reports. Prabh had researched the area and had the advantage of army survival training, but he had set out without a GPS device or powerful personal locator beacon.

The discovery of a water bottle bearing the logo of a scuba diving company Prabh had dived with could have been a signal of his whereabouts but there is no indication he took specialist snow gear, adequate food or any kind of shelter.

Although National Parks officials warn against hiking alone, the practice is common.

The search began on Monday, May 20, exactly one week after Prabh went missing. Temperatures hadn't risen much above zero, and snow was up to 30 centimetres deep.

It would not be a simple mission.

About 50 kilometres down the mountain in Jindabyne, NSW Police set up a command centre in the National Parks and Wildlife Services building. Sitting side by side with park rangers in a series of offices opposite the visitor centre, police began to map out the plan for a search area that stretched over about 11,000 hectares of rough, mountainous terrain. The Srawn family was never far away - staying in a hotel across the road, they spent long periods in the building's conference room, being briefed by authorities and watching over the work being done to find Prabh.

Local police and park rangers were joined by Victorian and Australia Federal Police officers and alpine specialists, State Emergency Service volunteers, firefighters, and ambulance crews on the ground, and Polair, and two rescue helicopters in the air.

Planning for each day would start the morning before, with rosters, maps, and any new pieces of information. Local police Inspector Peter Rooney, one of the search coordinators, says the days have been long, and the work exhausting.

Work begins about 6am, with briefings at 7am, and then teams make their way to allocated search areas by air, road, foot, and snowmobile.

"We've had a number of instances where the staff have deployed on snowmobile, and haven't been able to get anywhere near it, so they've had to walk for an hour or two to get into where they are," Rooney says.

As many as 30 people were in the field at any given time, divided into teams, and sent into terrain where visibility through snow and thick undergrowth could be as low as five metres, and temperatures as low as minus 13 degrees.

Conditions were prone to change quickly, and crews had to be well prepared. Each team carried GPS trackers, satellite phones, and police had emergency beacons and other survival equipment.

In some areas ropes and harnesses were needed to traverse slopes up to 70 and 80 degrees steep.

Looking for any sign of Prabh - equipment, activity, or even audible clues - crews would spend days scouring areas marked out as grid references on maps, reporting in every half hour or so. They aimed to wind up each day's search about an hour before sunset, but teams often had to be pulled out earlier due to aerial logistics, or adverse weather.

Some areas were impossible to access by foot. Helicopters would spend hours scanning hills and gullies, sometimes carrying thermal imaging technology. At one stage a sound - thought to be the voice of a man - was heard, prompting a refocused search, but nothing was found. The last of the three helicopters was pulled out on Friday.

At the end of each day, search crews would reassemble to debrief. Tens of thousands of points of GPS data would be downloaded onto National Parks maps, plotting every step on the ground, and every sweep through the air. Work would continue late into the night.

Snowy River ranger Luke McLachlan helped analyse maps of the terrain, which are more often used by National Parks for pest control and fire prevention planning rather than search and rescue.

The high-range mapping software can be toggled to show topographic details, relief of the terrain, aerial photographs, and National Parks assets including thousands of individually numbered snow poles, walking tracks, water courses, snow huts, and more. McLachlan says they can then export information to portable devices to use in the field.

"If people are out there with their personal iPhones, whether they're ambos, firies, or SES, they can have that on there and use that for navigational assistance, or we can take tracks off those sorts of equipment as well as GPS and put them on [the maps] so we can see where people have been," he says.

The National Parks team has been heavily involved in planning each day's work based on the multitude of information constantly being fed back into the maps.

"[Planning is] usually done with whatever [information] we've got, so early on that was basically where we think he might have gone, and where he could have gone wrong. As it's developed we've been downloading the track logs off the GPS from the search parties, so we can see where they've searched. We're downloading the data off the aircraft that have been flying around, both searching and deploying crews, so we're just picking up gaps in those tracks to see where we might need to put more effort in," he says.

"Of course the topographical maps don't have anything related to seasonality, to snow, so we're doing estimates of where the snow line is … we have had to exclude some areas from the ground searching, just because of the steepness of the terrain and it's unsafe for that sort of activity, so we've concentrated the aircraft there."

New information is factored in as it comes to hand - including from Vodafone, who traced Prabh's last known mobile phone connection, and from his computer which provided clues on his intended path. The technology behind a modern search mission means there is a lot of data.

"We end up swimming in it, sometimes drowning, but it's more useful than not having it. We can see those holes or areas that may have been missed, or may need to be more targeted," McLachlan says.

Inspector Rooney says everything is being recorded, and constantly reviewed.

As new leads dry up and signs of life fail to materialise, thought is turning to what happens next.

"The two sides of it, we're gathering as much information as we can to try and give us a picture of what's occurred, as well as looking for him," he says.

"At the end it gets put into a big folder and it sits there. If he hasn't survived it goes to the coroner, if he has, it goes through for our own information. It gets reviewed by senior management, it's looked at, as everything we do, it's something we can review to see if we can do things better, take out what we did well and incorporate that into the procedures for searches."

As far as the Srawn family is concerned, the search is far from over, and hope is far from lost.

Frustration, however, has grown as each day passed.

Sitting outside her family's hotel room overlooking Lake Jindabyne on a cool, cloudy afternoon, Mandeep recalls her devastation when police announced plans to scale back the search effort earlier this week.

She believes that Prabh, with his mental strength, penchant for organisation, and military and survival skills, could live well beyond the 14 days some experts gave him. She says the search shouldn't be wound down - it should be ramped up as Prabh's chances of survival decrease.

"We're trying to be as positive as possible; we know he's fine," she says.

"We're just let down by local search efforts, and even our government … I don't understand how, in this whole country, there are only 20 people who know these mountains and can walk them. I don't get it."

From early on in the search, Mandeep, Rajveer, and a huge group of family, friends, and vocal supporters in Canada, the United States and Australia have turned to the internet to raise awareness of the case, and to pressure Canadian and Australian authorities to increase search resources.

Using the only tools at their disposal - tweets, Facebook posts, petitions, prayer vigils and a prominent call for political action - family, friends and willing strangers around the world have called for more search resources, high-level intervention and precious awareness of their missing Prabh.

Politicians from Canadian Prime Minister Stephen Harper to Eden-Monaro MP Mike Kelly have received dozens of representations to get involved.

There is just one week left before the ski season begins; the June long weekend has traditionally been seen as the definitive start of winter in the mountains, when snowfall becomes regular, temperatures drop further, and the rugged mountain peaks become that little bit more remote.

With the command post at the NSW Parks and Wildlife Office closed down on Thursday, what is left of the search operation was handed back to the local police station.

The Srawn family also moved to hire a private search firm to keep men on the ground as public resources were gradually pulled.

What had been daily updates from NSW Police has been passed to duty officers in Jindabyne and Queanbeyan, but the Srawn family have no intention of returning home without Prabh. They'll stay until he is found, however long that takes.

"He couldn't have just disappeared, he must be out there," Mandeep says. "I told [police] if they're so confident [he's dead], then they need to show me a body. Then this will be all over."