Prosecuting Chris Dawson for murder in connection with the 1982 disappearance of his wife Lynette does not depend on finding her body, police say.
Thirty-six years after the Sydney mother vanished, police on Wednesday announced a five-day "forensic search" at the Bayview home she and her husband shared in the 1980s.
Since the release of The Teacher's Pet, a podcast by The Australian newspaper about Lynette's disappearance, there has been significant renewed interest in the murder on Sydney's sleepy upper northern beaches.
A senior police source told Fairfax Media that "100 per cent" of the reason for the new dig was public pressure that had come about following the podcast and subsequent media and public interest in the case.
But the source warned that the interest in the ongoing and active police investigation had come at a cost.
Witnesses have told police and the podcast two different versions of events, the source said, and some of the information used in the podcast came from a clairvoyant.
Police remain hopeful that investigators from Strike Force Scriven, which was formed in 2015 to re-investigate Lynette's disappearance, will secure enough evidence to prosecute Mr Dawson for his wife's murder.
Previously, the state coroner twice found that Mr Dawson most likely killed his wife, but the then-director of public prosecutions declined to prosecute, citing a lack of evidence.
Mr Dawson was never charged and has maintained he had nothing to do with his wife's disappearance.
"In April, I wrote to the director ... since then, we've found a lot more evidence and I've put that to the director," Homicide Squad Commander Detective Superintendent Scott Cook told reporters on Wednesday.
When asked how the new dig differed from previous ones, Superintendent Cook said: "Today we're digging in four areas. It'll be more extensive; we're using new technologies.
Superintendent Cook said there was "a lot of work to be done" by detectives.
"It is a complex block of land because it's largely rock and so digging is not easy; digging about 300-400 millimetres down is about as far as we're going to get in most areas."
The strike force had copies of the house plan, as well as detailed information about subsequent renovations and additions, he said.
Superintendent Cook said Mrs Dawson's family had been kept updated on the police investigation.
Her nephew David Jenkins said it was "hard to describe how I'm feeling" about the news of a fresh dig. "A mix of apprehensive and hope", he wrote online.
Latest in a series of inquiries into disappearance
The first coronial inquest in 2001 to look at what happened to Mrs Dawson recommended charges be laid against a "known person", but the then-NSW director of public prosecutions Nicholas Cowdery, QC, declined to prosecute due to a lack of evidence.
A 2003 coroner's inquiry into Mrs Dawson's disappearance led to then-deputy state coroner Carl Milovanovich recommending that a "known person" be charged with murder.
The inquest revealed Mr Dawson, then a teacher at Cromer High School on Sydney's northern beaches, had sexual relationships with his students.
One affair was with Joanne Curtis, then a 16-year-old student who moved into the family's home two days after Lynette went missing and later became his wife.
Again, Mr Cowdery declined to prosecute.
Mr Cowdery told the ABC's Australian Story the case against Mr Dawson was "weak" without a body.
"Without a body, without knowing first of all whether in fact she is dead, without knowing secondly if she is dead, how she died, it's very hard to mount a case of a reasonable prospect of conviction just on motive and the undefined existence of means and opportunity. That makes it very weak," he said.
"Lyn Dawson disappeared, and that really is as far as I can take it in my own mind."
Strike Force Scriven was established in 2015 by detectives from the Homicide Squad's Unsolved Homicide Unit to again investigate Mrs Dawson's disappearance.
High school sweethearts, Lynette and Chris Dawson married after meeting at Sydney Boys High and Sydney Girls High and went on to have two daughters and build a home at Bayview.
Just weeks before her daughter was due to start kindergarten, Mrs Dawson simply disappeared and has not been seen or heard from since.
Mr Dawson did not report his wife missing for almost six weeks.
In the interim, one of his teenage students moved into the family home the day after Mrs Dawson's disappearance.
The ABC reported he used Mrs Dawson's eternity rings and engagement ring to make a new engagement ring for Ms Curtis.
He later moved to the Gold Coast with Ms Curtis, where the pair had a child together. Ms Curtis left Mr Dawson after six years of marriage.
Mr Dawson now lives in Noosa with his third wife, the Gold Coast Bulletin reported.
Rachel Clun is a reporter at the Sydney Morning Herald. She was previously a reporter with the Brisbane Times and Domain.