An inquest will be held to examine one of New Zealand’s most baffling missing persons cases.

Swedish-born helicopter pilot John Beckenridge broke a court order and picked up his 11-year-old stepson, Mike Zhao-Beckenridge, from his new Invercargill school on March 13, 2015.

The pair vanished soon after and have never been seen since.

However, Beckenridge’s dark-blue 4WD Volkswagen Touareg went off a 90m cliff near Curio Bay a week later.

It took police six weeks to recover the battered wreck from the treacherous waters and there was no sign of any bodies.

Many Southland locals, as well as friends and neighbours, have previously believed that Beckenridge staged their deaths and that they were hiding out either in New Zealand or overseas.

Police have spent thousands of hours investigating the case but have had no success in finding out exactly what happened.

Now, a coronial inquest has been ordered and will begin in Christchurch on May 22.

Mike Zhao-Beckenridge disappeared with his father. Photo / Supplied

Coroner Marcus Elliott will look take a fresh look at the case.

Mike would now be aged 18.

Beckenridge, a helicopter pilot, met Mike’s mother, Fiona Lu, while they were working in Afghanistan in 2006. Lu, who is from China, had moved to the war-torn country to work as a waitress, with her parents raising Mike.

The pair later moved to New Zealand where they were based in Queenstown. Their relationship broke down in 2014 shortly after Lu moved to Invercargill to begin a hairdressing course.

Mr Beckenridge's car was found at the bottom of an 88m cliff near Curio Bay. Photo / Otago Daily Times

Lu told the Herald on Sunday earlier that she was adamant her son was alive.

“There is not a single day I don’t think of him. I love him deeply. And for my part I am sorry for what has happened,” she said.

Over the years, police have received multiple sightings of the pair reported to them by members of the public across New Zealand, Indonesia, and other countries.

Beckenridge, who was living in an upmarket Queenstown estate before disappearing, was well-known in Papua New Guinea flying circles.

Pilots recall an experienced, talented and popular commercial pilot, who also flew in Afghanistan and is believed to have several aliases, including John Locke, John Robert Lundh, Knut Goran Roland Lundh and John Bradford.

Pacific Helicopters PNG chief executive Mal Smith, his former boss who has been interviewed by New Zealand police, said he knew Beckenridge had been having “problems getting access to his kid but we didn’t know it was to that extreme”.

Aviation expert Peter Clark has said it would be “improbable but not impossible” to flee New Zealand by helicopter.