Chris Dawson's possessiveness of his teenage babysitter meant his claims of innocence after being convicted of murdering his wife should be rejected, a court has been told.
The 75-year-old is trying to overturn an August 2022 NSW Supreme Court murder verdict by Justice Ian Harrison, who found the ex-teacher killed his wife Lynette and disposed of her body in January 1982.
The judge found Dawson committed murder because he was so infatuated with pursuing a teenager who worked as his babysitter that he had to get rid of his wife.
On Tuesday, crown prosecutor Brett Hatfield SC said the judge had made the correct decision.
"There is not a significant possibility that an innocent person has been convicted in this case," he told the NSW Court of Criminal Appeal.
Dawson's claims his 33-year-old wife abandoned the marital home and her two children because of his pursuit of a teenage high-school student should be rejected, Mr Hatfield said.
Ms Dawson had not spoken to or been seen by anyone since January 8, 1982 and had idolised her husband and adored her children, a three-judge panel heard.
She had an "unwavering commitment" to her marriage despite it crumbling around her and had no reason to cut contact with her family and friends, Mr Hatfield said.
On the other hand, Dawson had shown he wanted his relationship with the girl, who can legally only be identified as JC, to be permanent.
Referring to the relationship between student and teacher as an "affair" was an understatement, the prosecutor said.
"It's not an affair," he told the court.
"It's an obsessive, possessive relationship between (Dawson), the former teacher of the girl that turns 18 only at that time."
Dawson watched the hearing by video-link from Clarence Correctional Centre, near Grafton.
Earlier on Tuesday, his barrister Belinda Rigg SC challenged Justice Harrison's verdict by saying her client had shown he was already willing to lose the relationship with his wife to be with the teenage student.
"He was no doubt capable of continuing that relationship, if JC was willing to, regardless of his wife," Ms Rigg said.
She argued the teen had said she did not want to continue the relationship with Dawson after they tried, unsuccessfully, to start a new life together in Queensland.
"The impediment to the relationship continuing was JC, not his wife," Ms Rigg said.
"Lynette Dawson had never been an impediment so far as JC was concerned."
On the other hand, there was a reasonable possibility Ms Dawson had left the home to take time for herself because of the mental anguish caused by her husband's pursuit of his student, the barrister argued.
Dawson claims he dropped his wife off at a bus stop and received a phone call from her the following day in which she said she needed time alone to think things through.
Ms Rigg said this was still a possibility and Justice Harrison could not find Ms Dawson was dead on January 9 and that her client had committed murder beyond reasonable doubt.
She told the three judges her client suffered a significant disadvantage in having to defend 40-year-old allegations and his prior good character needed to be taken into account.
But Justice Christine Adamson questioned whether his character should be given much weight considering how he conducted himself with the teenager while working as a teacher with students under his authority.
Ms Rigg said the court could consider Dawson's non-violent and non-aggressive nature.
Justice Harrison sentenced the ex-Newtown Jets rugby league player to a maximum of 24 years in prison for his wife's murder.
Dawson's full jail stint will expire in August 2046 and he will be able to apply for parole in August 2041.
If his appeal succeeds, the court could either acquit him of murder or order a retrial.
The hearing continues on Wednesday.
