In 1963, Margret and Gilbert snuck off to Sydney's ‘lovers' lane’. The next day, they were found dead.

In the wee hours of the morning on New Year's Day in 1963, Margaret Chandler and Dr Gilbert Bogle snuck away from a high-society party in Sydney.

The pair were both married to other people and had only met 12 days earlier.

Chandler was a mother-of-two and wife to CSIRO scientific photographer Geoffrey Chandler, who worked with Dr Bogle – a respected physicist and father.

Aware of his wife's attraction to his co-worker, Geoffrey left the party in Chatswood to spend time with another woman he was seeing on the side.

At around 4am, Chandler and Dr Bogle also left the party, driving to the Lane Cove River, where they made their way towards a narrow dirt track on the riverbank - a secluded spot known locally as 'lovers' lane'. 

Hours later, the pair were found dead, half-naked and metres away from each other. The mystery of their demise quickly become front page news, and in the decades since, have been the subject of podcasts, books and a film. 

The mystery has endured for the past 60 years.

The discovery of Dr Gilbert Bogle and Margaret Chandler's bodies. 

Hours after Bogle and Chandler left the New Year's Eve party, two boys out walking near the river stumbled upon Dr Bogle lying face-down on the ground.

The boys, who were out looking for golf balls, thought the man was drunk after a night of New Year's Eve festivities so left him and walked on. But when they returned an hour and a half later, they noticed Dr Bogle's face had turned purple and quickly alerted the police.

When officers arrived on the scene, they found Dr Bogle's body, naked from the waist down. His suit trousers had been placed over his lower body and he was covered by a piece of carpet. 

Dr Gilbert Bogle. Image: 7.30 

More than 10 metres away, on the bank of the river, they found Chandler's body. 

Like Dr Bogle, she was half naked, covered by a piece of cardboard. Her party dress was muddy, as were her feet and knees. 

The pair's underwear, along with a belt and shoes, were also found nearby.

Margaret Chandler. Image: 7.30

The scene wasn't like anything police had typically come across before.

"[It was] absolutely bizarre," podcast host and investigative filmmaker Peter Butt previously told Mamamia's True Crime Conversations podcast.

"These two people have gone down [to the bed of the river] for privacy. They'd half undressed in the process of making love and something happened."

There was no injuries or evidence on either of Chandler or Dr Bogle's bodies to suggest what killed them, and an initial autopsy didn't provide any answers. 

"They either stopped breathing or their hearts stopped, but there was nothing identifiable at the autopsy," said Butt.

Not knowing who killed the pair, police were left to hunt for an unknown killer as Chandler and Dr Bogle's organs were sent away for testing.

The theories surrounding Chandler and Dr Bogle's deaths. 

Geoffrey Chandler.

Police quickly turned their attention to Chandler's husband, Geoffrey.

Despite the fact that the pair were in an open marriage - an unusual type of relationship in the '60s - it was initially thought jealousy may have played a role in their deaths.

"From the start, the police just said, '[Geoffrey] has had to have done it. How did he do it, is the question,'" Butt told Mamamia. 

Shortly after police discovered the bodies on New Year's Day, Chandler's husband was woken and taken to Chatswood police station, where he was presented with a newspaper informing him of his wife and Dr Bogle's deaths.

"He was in such shock that he just froze... [Police] tried to heavy him into admitting it. But he couldn't admit to anything because he didn't do it."

Geoffrey had an alibi, having spent the night with his girlfriend on the other side of the city.

"He had no reason to kill his wife. They had a nine-month-old baby and a two-year-old. Why would he do it? He could not believe that they didn't respect the fact that they had an open marriage. Police and the media could not relate to that."

The greyhound trainer.

Another suspect that emerged was a local greyhound trainer, who was known to take his dogs to the river early in the morning for a run, away from the public. The man's car was also identified as being at the track the morning of Chandler and Dr Bogle's deaths. 

But as Butt pointed out, he had "no motive" to kill the pair.

Instead, police suspected him of covering the bodies with the carpet and cardboard that morning, despite the fact he denied seeing the bodies. 

"He probably didn't know that they were dead at that stage, because it was just after the event would have occurred," said Butt.

"He's never admitted that but his family was suspicious because he came home very, very anxious... They said that their father was a prude [and that] he hated the sight of bare flesh."

Poison. 

Police also suspected Chandler and Dr Bogle may have been poisoned after finding vomit and excrement near their bodies by the river.

However, forensic examination failed to find any traces of toxic material. 

"It was left to the toxicologist who had very limited resources to be able to deal with looking [for the poison]... He spent 13 months literally day and night... He went through every possible poison looking for the killing agent. He spoke to experts around the world, in the FBI and in Britain, and they couldn't help him."

"It was his last case; he had to give up after that the failure of not being able to find the answer."

The only thing that was known for sure? "Whatever killed one killed the other, and at the same time."

Decades later, Butt carried out his own investigation on the river itself and came up with a theory, which he shared in his 2006 documentary, Who Killed Dr Bogle and Mrs Chandler?

Butt suggested the pair died from asphyxiation caused by exposure to high levels of hydrogen sulphide in the river, which reportedly came from the dumping of waste by a nearby factory.

"I discovered that there was this whole history of this river where [hydrogen sulphide gas] was emanating out of the mud... and it had been doing that throughout the 1940s to such a degree that the local council were going to have to evacuate the houses near the river because people couldn't breathe at night."

"So they called in a Maritime Services Board scientist to find out what the source of the problem was and they discovered that the river bottom itself was saturated in hydrogen sulphide gas," said Butt, who added the gas is "as toxic as cyanide gas".

"It's heavier than air and in the cool of the morning, it hovers basically at ground level. If you were lying in that you could die."

During Butt's investigation, the scientist who originally worked on the case also told him something he'd never told anyone before – all those years ago, he the blood found on the bodies had a purplish discolouration that he couldn't explain.

"I was the first person outside of his boss that he'd ever told about this. I knew what that purple discolouration meant... it is one of the symptoms of hydrogen sulphide poisoning."

Listen to Peter Butt's full interview on True Crime Conversations. Post continues below. 

The case remains unsolved.

While Butt's theory explained the purplish colour of the blood, a lack of tissue and blood samples means it can't be proven today.

Still, he was able to offer some sense of closure to Geoffrey and his family.

"He was speechless when I told him the story. And he just said 'it's the only thing that makes sense'. And he was pleased. I [also] met with one of his sons, and he seemed to be appreciative that we've come up with something that at least proved that the father wasn't the culprit."

The Bogle family also appreciated Butt's discovery. 

For decades, both families had been impacted by the "unrelenting" coverage. 

"I think it ruined reputations, it ruined lives," said Butt. 

"[Geoffrey] had given up on the media, he'd given up on everybody. His life was completely ruined, his children were affected and the children of Dr Bogle were affected."

Six years after Butt's film, a retired physiologist contacted him with another vital piece of information. 

The physiologist had rescued a young girl from being assaulted in a park, years after Chandler and Dr Bogle's death, who had been at Lane Cove River the morning they were killed. 

"She witnessed two people asphyxiate and she couldn't come forward because she was down there for the same reason as Dr Bogle and Chandler were down there at lovers' lane. She didn't realise that they died but the information that she gave beautifully dovetailed into the theory of hydrogen sulphide poisoning."

Sixty years on, the case remains unsolved. And despite the reliance on circumstantial evidence, Butt and the families would like to see an inquest happen finally get answers and lay the case to rest.

"I don't care if they say 'it's all circumstantial'. It's the only evidence that we've got. [Then] it's on public record, it's out there. The world is listening."

In the meantime, Butt sums up the case as a "misadventure" rather than a murder.

"It was two people in the wrong place at the wrong time."

Feature Image: 7.30

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