As the murder trial against Christopher Michael Dawson, 73, enters into its closing phase, crown prosecutor Craig Everson SC explained how evidence of the bruising could lead the NSW Supreme Court to find Mrs Dawson was killed instead of just leaving home.

Mr Everson said the Crown was attempting to show Dawson had three tendencies through its evidence: that he had an animosity towards his wife, that he had contemplated using a third party to kill her, and that he wanted the school student he was having an affair with, known as JC, to be his wife and the mother of his children.

The barrister described testimony that Mrs Dawson had been seen with black eyes, and bruising on her arms and legs as a "small piece of a larger mural of circumstances".

"The unexplained bruising from those people is just simply a fact to be taken into account as a strand in the cable," he told Justice Ian Harrison on Thursday.

Circumstantial evidence had also been used in the 1980 trial of Adelaide woman Emily Perry who was accused of attempting to murder her husband using arsenic-based weed killer.

In that trial, evidence was shown of previous husbands who had the unfortunate habit of dying from arsenic poisoning, Mr Everson said.

Dawson's solicitor Greg Walsh argued that this type of evidence should be set aside, saying that guilt could not be found using testimony which was in doubt.

"The evidence at this stage, for instance in relation to bruising, is so tenuous, so imprecise, so speculative, that Your Honour would not be so satisfied in respect of those acts occurring," he told the judge.

Mr Walsh argued that evidence by JC and Robert Silkman claiming Dawson had tried to hire someone to get rid of his wife should be viewed with scepticism.

JC's allegations her former husband had inquired about a hitman were first made in 1990 during a bitter custody dispute, the court heard.

Silkman's claims could also not be trusted because he was a convicted criminal who frequently lied, Mr Walsh argued.

"He was a rogue. He took advantage of other people who were vulnerable. He freely admitted to putting up false alibis, lying to police, lying to medical practitioners, lying to juries, lying to judges," the solicitor said.

Justice Harrison also grappled with other evidence presented in the case so far, including testimony given by one of the Dawsons' former babysitters that he had flicked Mrs Dawson with a tea towel in their kitchen.

"Some people might argue that it's a pretty long drive through a dark night to contend that flicking someone with a towel is associated with killing them," the judge said.

"They would and they'd be right but it's not relied upon to prove that," Mr Everson replied.

The court also heard further audio records of police intercepted phone calls between Dawson and those close to him in the months before his arrest in December 2018.

In one of those calls, Dawson lamented the impacts the murder allegations had had on his family, who were concerned he might kill himself.

"I won't. I wouldn't give them the satisfaction," Dawson said.

He was heard saying the family should launch a class action over the harassment.

In the calls, Dawson blamed JC for making up lies about him to the police because of a heated custody dispute.

He also accused the investigator who handled the case from 1998 to 2015, former detective Damian Loone, of wanting to resurrect his career. He alleged the police officer went to a party with a noose around his neck to make fun of an Indigenous Australian man who had hanged himself in custody with a football sock.

Dawson has pleaded not guilty to the charge of murder and denies having any involvement in his wife's disappearance.

The trial resumes on Monday.

Australian Associated Press