Christine Ann Lyons, 47, and Ronald Lyons, 45, are each charged with one count of murder and one count of attempted murder in relation to the death of Ms Kelly, 39, at a Wesley Street, Kangaroo Flat address about January 23.

Both have pleaded not guilty to the charges.

OUTCOME: Jury finds Christine Lyons guilty of Samantha Kelly murder

In her opening address on Monday, Crown prosecutor Fran Dalziel said the prosecution’s case was that Mr Lyons and another of their housemates at the time, Peter Arthur, were devoted to Ms Lyons.

Ms Dalziel told the jury the three people planned to kill Ms Kelly so that Ms Lyons could parent Ms Kelly’s four young children, who at the time of the murder were aged between six years old and 11 months old. 

“Christine Lyons was unable to bear children herself and she was desperate for children of her own,” Ms Dalziel said. 

“She wanted to raise Samantha's children as her own children.”

In establishing the prosecution’s case for the motive, Ms Dalziel told the jury that Mr Lyons and Ms Lyons had already tried to claim guardianship of two girls under the care of the Department of Health and Human Services, and that Ms Lyons had asked a neighbour to have a child for her.

The jury was also told that Ms Lyons discussed with the father of Ms Kelly’s youngest child her desire to take on the care of that child and possibly all the children.

Ms Dalziel told the court that in December 2015, a close friend of Ms Kelly and Ms Lyons, and cousin of Mr Lyons, was privy to discussions in which Ms Lyons spoke of her wish for Ms Kelly to “disappear”, and Mr Arthur and Mr Lyons discussed ways of killing her.

She said that from mid December 2015, Ms Kelly began telling friends and her brother Michael that she “needed to get out of there” and that her housemates were planning to kill her.

She told the court that around New Year’s Day 2016, Mr Lyons, Ms Lyons and Arthur tried to kill Ms Kelly by crushing up pills in liquid and having her drink it.

Later that month, Ms Dalziel said, another attempt was made to cause Ms Kelly to suffer a fatal overdose with a cocktail of drugs.

But when that did not work, she told the court, the accused and Arthur came to an agreement that something else needed to be done.

“Peter Arthur armed himself with a hammer and struck Samantha to the head at least six or seven times,” Ms Dalziel said.

“These blows to her head killed her.”

Arthur later partially buried Ms Kelly’s body in a dry creek bed at Shelbourne.

Christine Lyon’s defence lawyer, Peter Kilduff, said there was no dispute that Peter Arthur had killed Samantha Kelly with a hammer.

“But our position is this: is that when Peter Arthur committed that crime, he was acting alone,” Mr Kilduff said.

He said Ms Lyons was not involved in the murder of Ms Kelly, nor any previous attempts to take her life.

He told the court she also denied the motive put forward by the prosecution.

“She denies that she was motivated or desperate to have her own children and importantly to kill for it,” Mr Kilduff said.

He told the jury they needed to put emotion to one side, and stressed that it was the prosecution that had to prove the case beyond reasonable doubt.

Mr Kilduff also reminded the jury that Ms Lyons was presumed innocent by law.

Jarrod Williams, Mr Lyons’ lawyer, also told the jury that Mr Lyons was not party to any agreement to kill Ms Kelly, and Arthur was not acting on his direction.

“He did what he did on his own and for reasons known to him,” Mr Williams said of Arthur.

He said it was disputed that Ms Lyons was so desperate to have children she was prepared to kill, and also that Mr Lyons was devoted to her in such a way that he would help kill to assist her.

“It may well be the case that Christine Lyons had a very strong emotional desire to have children,” he said.

“It may well be that she enjoyed being a mother figure to Ronald's children, perhaps even to Samantha's children but we say the suggestion that she was prepared to kill Samantha so she could take on the care of her children is just not true.”

Mr Williams said there was no discussion around New Year’s Day about killing Ms Kelly with drugs.

He said Mr Lyons had no idea Arthur was going to kill Ms Kelly, and while he found out afterwards and did not go to police, it did not make him complicit in the murder.

After January 23, Ms Dalziel said the accused and Mr Arthur told others that that Ms Kelly had left in the middle of the night, had left with a man, had abandoned her children and been physically violent towards them, and had showed signs of drug use.

She told the court they also used different names for two of Ms Kelly’s children.

After his arrest in February 2016, Ms Dalziel said, Arthur gave various versions of what happened to police, but admitted to killing Ms Kelly.

She told the jury that Ms Lyons said to police she had not seen Ms Kelly after January 21, and that she thought Arthur had killed her, but she was in denial.

She told the jury that in Mr Lyons police interview, he said that Ms Kelly was abusive towards her children, and her ex-partner had threatened to kill her.

“He denied killing Samantha but he said he thought Peter Arthur may have done it,” Ms Dalziel said.

She said he told police he helped Arthur move the body from the unit, and later, that he bought the shovels for gardening.

He denied to police that he was involved in drugging Ms Kelly or suggesting she be injected with air, she said.

The trial continues.