THE mysterious case of a wife who vanished 36 years ago after discovering her teacher husband’s affair with a pupil is closer to being solved thanks to a chart-topping podcast.

The Teacher’s Pet examines how housewife Lyn Dawson disappeared from the suburban home she shared with ex-rugby star Chris and their two young daughters.

Even though Lyn’s body has never been found, two separate coroners in Sydney, Australia, have concluded that Chris killed her. The director of public prosecutions in New South Wales twice ruled there was insufficient evidence to charge Chris with murder.

Chris, who now lives in Queensland with his third wife, denies murdering Lyn — and bizarrely claims to have spotted her in the background of an episode of the BBC’s Antiques Roadshow filmed in Padstow, Cornwall.

But many people interviewed for the hit podcast are adamant that he was responsible for Lyn’s death.

Journalist Hedley Thomas, who put together the podcast investigation that has been downloaded 12million times, is certain that the 33-year-old former nurse was murdered.

He said: “I do believe that from the fresh evidence that I’ve discovered that Chris benefitted from what looks like the most extraordinary incompetence by Northern Beaches police.”

Thanks to the podcast — which also uncovered disturbing allegations that Chris was part of a teachers’ sex ring — a new police probe has been launched into the suspected murder after the case went cold for years.

Lyn and Chris’s story begins when they met in high school. They fell in love and married in 1970 when they were both 21.

Chris was handsome, charismatic and semi-famous, having played rugby league professionally for Sydney’s Newtown Jets alongside his twin brother Paul.

When his rugby career faded in 1979, he started teaching PE at nearby Cromer High School.

He and Lyn decided to start a family. They were a picture of happiness — young, beautiful and successful, and now with two adorable daughters Shanelle and Sherryn.

Lyn was devoted to Chris and the girls but friends became concerned when they started to notice bruises on her porcelain skin.

It was around this time that Chris had begun having an “intense sexual relationship” with 16-year-old Joanne Curtis, who was one of his students.He happily introduced his barely legal lover to his wife and kids. She became their babysitter, conducting the affair right under Lyn’s nose.

Vulnerable Joanne lived with her mum and stepdad, a violent alcoholic, in a tiny and cramped flat. She adored the attention she got from authoritative Chris.

It is alleged that her older lover arranged for the impressionable teen to have sex with his twin Paul — both alone and as part of a threesome with Chris.

Unaware of what was going on, Lyn encouraged the bond Joanne shared with her two daughters.

Years later, Joanne would say Lyn showed her “more kindness” than anyone else had up until then.Chris became cruel and distant towards his wife, and Lyn’s mother Helena Simms warned her that something was not right.

So Lyn confronted Joanne and allegedly said to her: “You’ve been taking liberties with my husband.”

In a police statement, Joanne claims she replied: “I didn’t know what to say,” and left the Dawsons’ home in the suburb of Bayview to stay with Chris’s twin Paul.

In December 1981, Joanne and Chris “ran away” to start a new life in Queensland. But she panicked and they returned to Sydney to continue their affair.

Then in January 1982, while Joanne was away with friends, Lyn vanished.

Chris claims Lyn had told him she was going away for a while and “not to worry about her”.

But just two days after his wife’s disappearance, Chris moved Joanne back into the family home.

The schoolgirl slept in Lyn’s bed — and to friends’ repulsion started wearing her clothes and jewellery.

Lyn’s little girls, just two and four, were confused and upset but started to call Joanne “Mummy”.

Four-year-old Shanelle told her grandmother Helena “Mummy has gone away” because she did not love them any more.

Aged five, Shanelle told Helena that Lyn had just been their pretend mum and their real mum was now Joanne. Shanelle, now a mother herself, told The Australian newspaper: “It was a taboo subject. If one of our cousins or someone mentioned her it was just kind of this uncomfortable silence.”

Shanelle’s relationship with her stepmother was, she says, “painful”.

She told the podcast: “She engaged with us a bit more when she was our babysitter. Then she became our mother and she was not very kind.

“You had to stay completely still while you’re having a hair brush and were whacked across the head if you so much as moved.

“I remember being locked in the laundry for not eating my dinner.”

Meanwhile Chris waited five weeks before reporting Lyn missing.

Among his vague explanations for where his wife might have gone was the suggestion that she had joined a religious cult.

Former neighbour Julie Andrews recalled: “When Joanne turned up I thought, ‘He’s got rid of her’.”

Two years after the disappearance Joanne and Chris moved to Queensland’s Gold Coast where they married — sickeningly, with Lyn’s wedding ring slipped on to Joanne’s finger.

They had a daughter, Kristin, together. But Chris soon turned his cruelty on to Joanne, who returned to Sydney alone in 1990.

She gave the police new information. Detectives questioned Chris at length and launched an investigation — but it yielded nothing.

Eight years later Lyn’s friend Sue Strath told police she suspected foul play. They dug up the couple’s garden at their former home and unearthed a cardigan with what appeared to be slash marks — but no body. In 2001 a coroner dramatically concluded that Lyn had been murdered by her husband, but the New South Wales DPP ruled there was insufficient evidence to charge him.

Two years later, another coroner reached the same verdict but again it was ruled there was insufficient evidence for a murder charge.

Now, thanks to the podcast’s investigations, new and ever-more disturbing revelations have come to light.

Former pupils at Cromer High allege that a “pack” of teachers had been having sex with students.

Robyn Wheeler, the school’s vice captain, recalled mothers confronting teachers to demand their daughters be left alone, and pupils being plied with alcohol and drugs.

A girl who attended a school Chris later taught at in Queensland said that the teacher had tried to groom many of her friends and would wrestle on the beach with bikini-clad girls as young as 13.

Carl Milovanovich, New South Wales deputy state coroner, thinks the original investigation did not give the case an “appropriate degree of attention” because police thought Lyn would return home in 48 hours — like most missing persons.

He believes that Lyn’s ex-husband is responsible, saying: “If you put all this evidence before a jury they would come back with a guilty verdict.”

The podcast has now been put on hold until new evidence is uncovered.

Meanwhile Lyn’s friends and family are left waiting for justice.

Daughter Shanelle said: “I’d kind of given up hope. It’s seemed like there were no other leads on anything that might lead to an answer as to what happened to my mum.

“So I’m hopeful that this might just keep the hope alive.”