NSW Police have commenced a forensic search at the former home of Lynette Dawson in Bayview, on Sydney's northern beaches.

Key points: Ms Dawson's disappearance is the subject of a popular podcast called "The Teacher's Pet"

Ms Dawson's disappearance is the subject of a popular podcast called "The Teacher's Pet" She has not been seen since 1982

She has not been seen since 1982 Two separate coronial inquests recommended a "known person" be charged with her murder

The search, which will take place across five days, will focus on four sites and include excavations, with police describing finding "anomalies" in the ground during previous efforts.

Ms Dawson, a mother of two, disappeared in 1982. She was 33 at the time and has not been seen since.

Her husband, PE teacher Chris Dawson, said she needed time away and a few days later, he moved his schoolgirl lover into the family home.

He did not report to police that his wife was missing for nearly six weeks.

Ms Dawson's disappearance has been the subject of two coronial inquests and intense media speculation, including a podcast.

The two separate coronial inquests recommended to the NSW Director of Public Prosecutions (DPP) that a "known person", identified now as Mr Dawson, be charged with her murder.

Despite the inquest findings, the DPP determined there was insufficient evidence to lay charges.

Mr Dawson continues to maintain he had nothing to do with his wife's disappearance.

Lynette Simms and Chris Dawson met at a high school function, both aged 16. They were both prefects. ( Supplied )

'Justice for Lyn'

Detective Superintendent Scott Cook said the family had been kept abreast of the investigation.

"It's the right time for us and for them. This is important that we do the best job we can," he said.

"This is all about getting justice for Lyn."

"We need to put our best foot forward and we need to make sure that the evidence we present is sound."

He said police were going to pursue charges against Mr Dawson regardless of whether they discovered any human remains.

"Absolutely, that's why I wrote to the director [DPP] in April," Superintendent Cook said.

Police said the search could come down to a "hand dig". ( AAP: Dan Himbrechts )

Four sites will be the focus of the renewed search, with excavations expected.

"Previously when we've conducted searches here there was a number of anomalies in the ground," he said.

"It is a complex block because it's mostly rock. We'll go to the bottom of the pool.

"At the end of the day, it'll be a hand dig."

Superintendent Cook said police had a "good understanding" of the property, and had radar equipment that could penetrate the ground.

A police officer sifts through soil at the former Dawson property on Sydney's northern beaches. ( Supplied: NSW Police )

"Digging is not easy, digging about 300 to 400 millimetres down is about as far as we're going to get in most areas," he said.

Neighbour Nancy Jiang, who has lived nearby for about five years, said she had not heard of the case until police arrived and told her some of the details.

"[It's] very scary and very sad," she said.

"I hope they find the body."

Chris Dawson and Joanne Curtis' relationship in the 1980s was the centre of a podcast by the Australian called The Teacher's Pet. ( Supplied )

Case previously considered 'weak'

Ms Dawson's story has been the subject of News Limited journalist Hedley Thomas' The Teachers Pet podcast, released this year.

Lyn Simms and Chris Dawson met as high school students and would go on to marry in 1970. ( Supplied: Simms family )

Nicholas Cowdery QC, who was in charge of the NSW's DPP at the time, this week told the ABC's Australian Story program he had good reason not to prosecute.

"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.

In April, police sent a new brief of evidence to the DPP which they hope will be enough to result in criminal prosecution.

NSW Police Commissioner Mick Fuller told Australian Story that was an "exciting step".

"We're still, with some passion, chasing the offender for this crime, and we sincerely hope that this year the matter will come to hopefully an end, a rather positive one," he said.

"If it doesn't, we'll continue to investigate the matter. We won't give up."