Husband of woman who vanished 36 years ago has 'nothing to hide'

She was the devoted mother of two, loving wife and caring sister her family simply adored.

He was the PE teacher, talented rugby league player and husband who was having a secret sexual relationship with a student.

But in 1982 everything changed when Lyn Dawson simply vanished from her home on Sydney's Northern Beaches and within days, her husband moved his 16-year-old lover into their house.

Lyn's family haven't seen or heard from her in 36 years, and believe they never will.

"I believe she was murdered, and by a known person," Lyn's sister Pat Jenkins, told A Current Affair reporter Chris Allen.

Two coronial inquests have found Lyn was indeed killed by a known person, her husband Chris, but no charges have ever been laid against him, with the DPP saying there isn't sufficient evidence.

In a world exclusive, A Current Affair tracked Chris Dawson down to ask him about his knowledge of his wife's disappearance, and the exchange quickly turned fiery.

Seconds after telling Chris Allen "she left" when asked what happened to Lyn, Chris Dawson and his brother Paul turned on the A Current Affair crew, putting their hands over the camera lens before attempting to shove the camera away.

Chris Dawson went on to say he had "nothing to hide" as his brother continued to leap to his defence saying Chris didn't have to explain anything about Lyn's disappearance or the affair he was having with a schoolgirl.

As they've done previously the pair now live just a couple of hundreds of metres away from each other, on the Gold Coast.

Chris Dawson went on to say it was "good" and he was "very pleased" that police have passed the case of Lyn's disappearance back to the DPP.

He has always maintained his innocence and right from the start told friends and family Lyn just up and left in January 1982, possibly even joining a religious cult.

It is an explanation Lyn's family has never accepted. 

"She was really excited about Shanelle (Lyn's daughter) starting school, she had a new uniform, she was really excited about that and she had already invited people to mum's birthday, a surprise birthday that was the beginning of February," her sister Pat Jenkins said.

Lyn's body has never been found but police did locate a cardigan, identified as Lyn's, buried at their former Bayview home, while carrying out a dig search beside the pool on the property in 2000.

Her family is hoping renewed interest in the case, following a podcast by The Australian's Hedley Thomas, could finally bring them the answers they've craved over the past three and half decades.