Former Sydney teacher Chris Dawson continued to love his wife before she vanished while also having a "relationship" with the family's teenage babysitter, a judge has been told.
Mr Dawson, 73, has pleaded not guilty to murdering Lynette Dawson in January 1982 and his legal team has argued she may have decided to walk out on her husband and two children.
The Crown has suggested he was motivated to kill Ms Dawson because he viewed her as an "impediment" as he pursued JC, the student babysitter with whom he was "infatuated" and would later marry.
A recorded police interview with Mr Dawson from 1991 has been played to the NSW Supreme Court, where he mentioned nights where he "lay awake, crying my heart out, hoping for some contact from Lyn".
Justice Ian Harrison today asked about the defence case regarding when Mr Dawson's marriage to Ms Dawson ended, given the accused's suggestion in the interview he was "yearning" for contact.
The judge — who is sitting without a jury — said he was mindful of asking questions because the defence did not need to have "an answer for everything". However, in assessing the force of the Crown case, defence submissions "can be of great assistance".
Justice Harrison said he understood the Crown to contend there was an inference that any "long and loving" relationship Mr Dawson had with Lynette Dawson ended long before January 8, 1982, when it has been alleged the murder took place.
"He was, at that time, in a fairly enthusiastic physical relationship with JC, if some evidence is accepted. Are the two inconsistent, or can they exist side by side?" Justice Harrison asked.
Mr Dawson's barrister, Pauline David, said they could co-exist.
"I mean, in France, it's a national sport," she said.
Ms David insisted Mr Dawson did love his wife, despite "issues and tensions" in their relationship.
In Mr Dawson's recorded police interview, he dismissed as an "utter fabrication" JC's allegation that he once drove somewhere south of the Harbour Bridge and said he went to get a hit man to kill Ms Dawson, before reconsidering because innocent people might get hurt.
He suggested she was trying to "slur his character" because of a "nasty" upcoming custody battle.
Justice Harrison said the Crown case was that it's "highly disrespectful to install one's lover in the house during the period of an existing marriage".
The judge said the Crown raised the issue due to inferences that he is being asked to draw about the circumstances around the time of the disappearance.
However, Ms Davis said "relationships" could co-exist before one was preferred over the other.
She also submitted it was "not such an unusual occurrence in human affairs" for someone to move on if they believed their wife had abandoned them.
The trial continues.
