And despite never being charged due to insufficient evidence, this person is thought to be Lyn’s husband Chris – a popular rugby player and school teacher.
Chris strenuously denies the allegations against him.
Lyn’s disappearance is the subject of a hugely popular podcast – The Teacher’s Pet.
On Wednesday morning, NSW Police announced they had begun a search of her $2.4 million home.
'As part of their ongoing commitment to providing answers to her family, Strike Force Scriven detectives have commenced a forensic search at Mrs Dawson's former home,' NSW Police said in a statement.
'In 2015, detectives from the Homicide Squad's Unsolved Homicide Unit established Strike Force Scriven to re-investigate the circumstances surrounding the 1982 disappearance and suspected murder of Northern Beaches wife and mother, Lynette Joy Dawson,' police said.
In an exclusive interview with New Idea this week, Michelle Walsh – who was a student of Chris Dawson’s at Cromer High School in Sydney’s northern beaches – speaks of her former friend.
‘I met Lynette at a gym display at the end of 1981,’ Michelle tells New Idea. ‘She was lovely, gentle. I remember her smile.’
Michelle recalls Chris as being ‘a rockstar’ at school, who used his position of authority by in the most shocking way – by starting a relationship with one of his Year 11 students, Joanne Curtis, who was then aged 16.
‘I was close to Chris so I was particularly aware of his relationship with Joanne,’ Michelle says.
‘When we were in his office Joanne would be sitting on his knee. When they shut the door my friend Michelle and I thought it was hilarious to play knock and run.
‘We’d hide in the stairwell in hysterics. Looking back it’s the weirdest thing. We knew he was married and had daughters, and had a girlfriend.’
Then on January 9, 1982, Lyn vanished and Chris moved Joanne into his home just days later. The children quickly started calling her Mummy.
‘I was training in the gym after the holiday break and Bushy came firing in, crying and shaking,’ Michelle remembers.
Bushy, or Miss Bush, was another of the PE teachers. ‘She was saying Lynette had gone missing. As a kid I had no idea what to say so I kept quiet and waited for her to leave.’
What happened when Michelle went outside is the fragment of information she has kept quiet about for so long.
‘Chris called me over,’ she remembers. ‘He demanded to know what Bushy told me. I didn’t know what to say.’
For more on what Michelle remembers from that shocking day read her exclusive interview in New Idea’s 8-page crime special – only in this week’s magazine.