Barbara Eckersley, who is on trial for the murder of her mother in a southern highlands nursing home, has told the Goulburn court she never discussed euthanasia in the context of her mother.
Acclaimed scientist Dr Mary White died in August 2018.
The day before her death, Ms Eckersley had laced her food with crushed temazepam tablets and on the day of her death she put so-called "green dream" barbiturate sedatives, left over from when she was a wildlife carer, in her food.
Dr White died four hours later.
Under close questioning by the prosecution today, Ms Eckersley conceded her mother was in a distressed state.
"She had no quality of life … in my opinion and in the opinion of many others," Ms Eckersley said.
Prosecutor Paul Kerr pressed her on whether that had influenced her actions.
"Is that why you ended her life?" Mr Kerr asked.
"I did not end her life," Ms Eckersley replied.
"You certainly contributed," Mr Kerr said.
"I may have," Ms Eckersley replied.
Ms Eckersley stood by her claim she did not intend to kill her mother, but wanted to ease her suffering.
A small stone mortar and pestle used to crush the tablets was passed around the jury along with a takeaway sauce container that had been used to transport the green dream drugs, which are used by vets to euthanase animals.
Ms Eckersley denied putting the drugs in the container to avoid detection by the staff.
Family told Dr White was not at end of life stage
Mr Kerr quizzed Ms Eckersley on why she had not told police about the drugs in her first interview.
She told the court she had been deeply depressed at the time and was not thinking rationally.
She described the feeling as an out-of-body experience.
The court also heard details of tensions between the staff at the nursing home and the family.
Dr White was being moved to a new home away from Ms Eckersley because the family had been concerned not enough was being done to ease her suffering.
Weeks earlier there had been a discussion with the staff about how Dr White was not at the end of life stage.
Ms Eckersley said there may have been some misunderstanding between the staff and the family over how Dr White's health should be managed.
A doctor who had treated Dr White told the court that Ms Eckersley's husband, Richard, had asked him about euthanasia in relation to his mother in law, well before her death.
The court heard Mr Eckersley was also an advocate for euthanasia.
But the court also heard he was gobsmacked when his wife told him what she had done.
The issue is one of the key differences between the defence and prosecution cases.
Though Ms Eckersley said her husband only discussed euthanasia in a general sense, not in the context of her mother.
