The disappearance of a young Belgian backpacker in Australia has confounded authorities for more than three years, and his fate remained a mystery after an inquest concluded Friday.

A coroner ruled that 18-year-old Theo Hayez likely died soon after he left a nightclub in the coastal town of Byron Bay, but she couldn’t say whether it was from an accident or if he was killed by others.

Suicide appeared to be highly unlikely and there was no reason for Hayez to intentionally vanish, said New South Wales State Coroner Teresa O’Sullivan. But she said she couldn't make a finding on the two theories put forward at the inquest into his disappearance.

One was that Hayez had a fatal accident as he tried to climb towards the lighthouse at Byron Bay. The other was that one or more people caused his death and disposed of his body.

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"Sadly, there is just insufficient evidence before me to substantiate or exclude either theory," O’Sullivan said.

Jean-Philippe Pector, the godfather of Hayez, told reporters outside the Byron Bay Court House that the family knew there wouldn't be any breakthrough after going through the inquest process, but they remained hopeful the "main question" would one day be answered.

'missing person' poster for missing Theo

Theo Hayez, a Belgian backpacker who was traveling in Byron Bay, Australia, is still missing. Hayez was last seen leaving Cheeky Monkey nightclub in Byron Bay, New South Wales, on May 31.  (MARIE-PAULINE DESSET/AFP via Getty Images)

"It’s obviously a really tough moment because it’s the end of a tough process," Pector said. "But I think it’s best that the case remains open, allowing new evidence to come forward."

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Hayez, who was preparing to return to Belgium after eight months of traveling around Australia, was last seen about 11 p.m. on May 31, 2019, after leaving the Cheeky Monkeys nightclub in Byron Bay.

Police were alerted six days later, when he failed to return to his hostel and could not be found or contacted.

A large-scale search was launched, but the only thing authorities found was a hat they believed was owned by Hayez.

Police in February announced a $313,000 reward for anyone with information about the case.

"I hope if there is any further information to be known, the reward would provide a motivation to come forward and contact Crime Stoppers," the coroner said.

O’Sullivan acknowledged the sadness and loss experienced by the family and friends of Hayez, some of whom traveled from Belgium to Byron Bay for the inquest.

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"It is obvious from the evidence he had a bright future ahead of him," she said.

Hayez's cousin Lisa Hayez told reporters that Byron Bay felt like the worst place in the world but also somehow like home.

"Like I was telling JP (Pector) driving here, I feel like I’m driving home, like I’m going home to my people," she said. "It’s very, very special and really hard to describe."