The death of a British man who died after opening “Pandora’s box” remains a mystery after an inconclusive official inquest.

The parents of Jason Airey, 37, of Carlisle, Cumbria, found their son unconscious, lying next to a box with “Pandora’s box” written on it. His heart stopped and he stopped breathing, and he died two days later. His death was in May, but the inquest was only completed recently and couldn’t determine why Airey’s heart stopped, the Cumberland News & Star reported.

His parents became concerned when Airey didn’t come out of their bedroom on the day he opened “Pandora’s box.” The term comes from Greek mythology, and represents all the evil in the world that escaped from the box (actually, a jar) after Pandora opened it.

Airey’s mother “went upstairs and came back down saying something was wrong. She couldn’t wake him,” Jason's father, Dennis Airey, told the British newspaper.

Dennis said nothing was out of the ordinary on the day his son died.

“He was just his normal self,” he said. “I think he had enjoyed himself in town. He had been shopping and said he was going upstairs to get changed.”

Inside the box was a bag of synthetic cannabis, but the substance wasn’t opened. Dennis Airey said his son had stayed away from drugs after a bad experience more than a decade before.

“It was a packet but had not been used. It was on the bed right beside him,” he said. “He hadn’t taken any drugs after having a bad experience with ecstasy 13 years ago.”

Coroner Robert Chapman said an autopsy on Airey found no trace of drugs in his system, and he ruled that Airey died of natural causes.

“His heart stopping caused the death of his brain, which caused multiple organ failure,” he said. “We don’t really know what caused his heart to stop. There is a possibility that he had a fatal cardiac arrhythmia – a change in his heartbeat.”