His body was never found – at least one expert believes the 25-year-old was dead before anyone knew he was missing.

On Friday, New South Wales coroner Harriet Grahame ruled the Canadian-born Bond University law student most likely died in the national park on or around May 14, 2013.

The finding follows a three-day inquest in Cooma last month, which heard the army reservist was happy and physically fit but likely unprepared for unexpected harsh weather conditions recorded near the Charlotte Pass Village and the Main Ridge Trail.

Offering condolences to Mr Srawn's family, Magistrate Grahame ruled his exact cause of death was unknown, but that it likely occurred "by misadventure of some kind."

Mr Srawn's final route was never clear but he is believed to have planned a short hike around Australia's two highest peaks, Mount Kosciuszko and Mount Townsend before driving to Melbourne in a rented van.

Likely wearing jeans, a T-shirt and a fleece jacket, an onset of blizzard conditions would have left Mr Srawn desperately unprepared. Hikers in the area reported setting out in fine conditions in the morning and struggling to walk in a straight line by lunchtime.

One experienced bushwalker said on May 14, even with GPS, a compass and a printed map, members of his group lost their way, becoming confused and disorientated in growing winds, rain and snow.

Magistrate Grahame's report includes new information about Mr Srawn's movements and the escalating search launched after his overdue rental car raised the suspicions of locals.

The full-scale search was not in place until May 21, nearly a week after Mr Srawn set out. Police were alerted by a local caretaker who noticed no movement around the rental van in heavy snow from the preceding days.

The 100 square kilometres scoured by police, SES crews and park rangers, included "extremely rough, diverse and challenging terrain" including exposed ridges, dense undergrowth, deep cracks and crevices, streams and cliffs.

Police running the search sought to "get inside Prabh's mind" and used mobile phone data to track his likely route. On May 22, National Parks and Wildlife Service crews reported hearing a voice in the area around the Opera House Hut on Lady Northcote Creek.

The hut – one of the earliest sites searched – was receiving maintenance when a faint noise was heard. Witness Mark Mitchell told the inquest he was certain it was a human voice, observed more than once above the sound of the creek.

Aware of a missing bushwalker, the group searched nearby and directed a helicopter scrambled to the area. Even with infrared equipment, it found nothing.

No activity was recorded from Mr Srawn's mobile phone after 3pm on May 14. Police told the inquest no physical evidence or administrative activity in his bank accounts, travel records or anything else was found.

The inquest found no reason to suspect a planned disappearance, suicide or foul play.

Survival specialist Paul Luckin said Mr Srawn could not possibly have been alive after 14 days in the conditions.

"I have no doubt that Mr Srawn was already deceased before it was known that he was missing," Dr Luckin said.

Magistrate Grahame found the search effort and investigation had been effective, before it was scaled back on June 1, 2013.

With "little trust" in the process, family and friends did not travel to Australia for the inquest. Believing a miracle was still possible, they offered only a short written statement.

The Srawn family spent more than $100,000 on private search efforts and at one time offered a reward for information.

Magistrate Grahame recommended the New South Wales National Parks and Wildlife Service consider improving timely information on its website, as well as reviewing and expanding educational material aimed at bushwalkers.

The report noted online information had described the Main Ridge Trail as a 12.5 kilometre walk, taking 4.5 hours. The track is actually 22 kilometres long, requiring 8-9 hours walking. The information has since been corrected.

Magistrate Grahame called on the service and NSW Police to immediately investigate a web-based trip intention lodgement system, similar to an overseas travel service offered by the Australian government.

The service should also consider ways of expanding and publicising its personal local beacon loan system for hikers in the Kosciuszko National Park.

Mr Srawn's family were contacted for comment.