Chris Dawson: How The Teacher's Pet podcast helped catch and jail a killer

Twenty-one years ago, journalist Hedley Thomas walked out of a Sydney police station blinking in astonishment.

Back then, few had heard of Lynette Dawson, a mother-of-two who had disappeared without a trace in 1982.

But Mr Thomas' perusal of her cold case that day set in motion a series of events that would make Lynette Dawson a household name. It culminated on Tuesday with her husband, Chris Dawson, convicted of her murder.

From the get-go, Mr Thomas said, he was struck by how absurd and "unjust" Mrs Dawson's story seemed.

"A young mother who was devoted to her daughters [was] being written off as a woman who didn't care about them, who just ran off… while her husband was conducting this extraordinary relationship with a schoolgirl half his wife's age," he told local broadcaster Seven.

As he dug deeper, his bewilderment only grew.

She had left with just a few clothes - no suitcase, no jewellery, not even her contact lenses.

And she had no job lined up, no car and little, if any, money.

She supposedly didn't contact anyone again except the husband who had betrayed and humiliated her.

"That is just completely ridiculous," Mr Thomas told the Australian Broadcasting Corporation, adding that "people would see through it today".

On Tuesday - 40 years after Mrs Dawson vanished - a judge in the New South Wales Supreme Court did.

Her body has never been found and the entire case hinged on circumstantial evidence.

But Justice Ian Harrison concluded that Chris Dawson - driven by an infatuation with his teenage babysitter, who was also a student at the school where he taught - had murdered his wife.

Although he first learned about Mrs Dawson's case in 2001, Mr Thomas didn't begin digging into it in earnest until more than 15 years later.

By then two coronial inquests had recommended "a known person" be charged with her murder, but prosecutors had declined, saying there wasn't enough evidence.

Mr Thomas began speaking to Mrs Dawson's friends, family and neighbours, and Dawson's teenager-lover-turned-second-wife, who is known for legal reasons as JC.

He also conducted extraordinary interviews with senior police involved with the investigation - including the state's police commissioner - and with a coroner who had presided over one of the inquests.

The podcast series he created for The Australian - The Teacher's Pet - touches on Dawson's affair, claims of physical abuse against his wife and allegations that he contemplated hiring a hitman to kill her.

It points out inconsistencies in Dawson's statements, paints him as a killer, and includes speculation about how he could have disposed of his wife's body.

Upon its release in mid-2018, the podcast - produced by Slade Gibson - was a huge success.

The series won Australian journalism's highest honour and has been downloaded more than 60 million times, topping charts around the world.

And within months of its publication, Dawson was finally charged.

Police had for years been pushing the case, to no avail, and many credited the podcast with finally securing some hope of justice for Mrs Dawson.

After the verdict on Tuesday her brother Greg Simms thanked Mr Thomas for giving his sister a voice and helping clear her name.

"She loved her family and never left them of her own accord. Instead, her trust was betrayed by a man she loved," he said.

But the podcast also ironically jeopardised the criminal proceedings against Dawson.

Dawson's lawyers argued - all the way to the High Court - for the case to be thrown out. The podcast meant there was no way he'd get a fair trial, they argued.

The courts found The Teacher's Pet was indeed problematic for several reasons, says Melbourne Law School Professor Jeremy Gans.

Firstly, it broadcast mountains of content - and speculation - that would not have been allowed as evidence in a murder trial.

There was concern the publicity surrounding the podcast would have prejudiced potential jurors, and had tainted witness testimonies.

Then there was the friendly co-operation between Mr Thomas and the police, which raised concerns about whether the journalist had influenced the prosecution.

And finally, there was what Justice Harrison on Tuesday called Mr Thomas' "less than balanced" approach to the story.

"Judges took the view that Hedley Thomas wasn't just being a reporter… he was pushing a narrative and very keen to convince everyone, including prosecutors, of Chris Dawson's guilt," said Prof Gans.

"Several said he just wasn't interested in the presumption of innocence, they questioned his ethics, and all sorts of things."

Mr Thomas has described some of the criticism of him as unfair, but, on advice from prosecutors, The Australian took down The Teacher's Pet podcast ahead of the trial.

The court delayed the trial, hoping that would give the speculation surrounding the case time to die down, and Dawson was instead granted a trial before a single judge, rather than a jury.

Both those outcomes were not ideal, Prof Gans says.

During the delay, potential witnesses died.

And trials before a lone judge are less likely to end in a conviction - judges, unlike juries, must explain their reasoning and tend to have a stricter definition of what constitutes reasonable doubt.

"For juries, the fact that you don't have to give reasons means that you go on your gut a bit more," Prof Gans says. "I always thought that a jury was likely to convict in this case but the judge was pretty unlikely to convict."

When the judge did convict Dawson, Prof Gans says he was surprised.

But, he adds, these kinds of verdicts are often easier to appeal.

"You've got these reasons that you can attack, and Dawson has that benefit now."

Lawyers for Dawson have already indicated he is likely to appeal.

In the end, Justice Harrison did find the podcast "may in whole or in part have completely deprived some evidence of its usefulness". He also disregarded much of the new information the podcast uncovered.

In the "best case scenarios", true crime series have solved cold cases, exonerated wrongly imprisoned people and exposed misconduct by investigators and prosecutors, Prof Gans says.

And that is exactly what Mr Thomas says he set out to do.

"This idea that the legal [and] criminal justice system can just manage this and not miss anything is a furphy - it's a lie," he told The Australian.

"There is always so much more material, so many more witnesses you could talk to, more evidence that can be gleaned. My overriding aim with these podcasts is to solve crimes."

Seeing that achieved on Tuesday was an "incredible relief", he says.

"When the hammer finally fell on Chris Dawson and he was declared guilty by the judge, it was a powerful moment," he told Seven.

"He's been scheming and manipulating and lying for at least 40 years. I hope that he is appropriately punished for it."

Dawson will face a sentence hearing on 11 November.