In a blow to the euthanasia movement, a jury has found one women guilty of the manslaughter and another an accessory to the manslaughter of Alzheimer's sufferer and former Qantas pilot Graeme Wylie.
Mr Wylie's partner Shirley Justins, 59, and his long-term friend Caren Jenning, 75, were accused of plotting to kill him.
Justins was found guilty of manslaughter and Jenning of being an accessory to manslaughter.
Mr Wylie, 71, died in March 2006 from an overdose of the veterinary drug Nembutal, which Jenning had bought and illegally imported from Mexico, and which Justins had given to him in their Cammeray home.
He had been diagnosed with Alzheimer's disease in March 2003 and the case centered on his capacity at the time of his death to decide he wanted to commit suicide.
Evidence on this had been conflicting and the jury deliberated for three days after the six-week trial.
The prosecution had argued Mr Wylie, who had been assessed as suffering from moderate to severe dementia, and who, four months before his death, could not remember the number or sex of his children or his own date of birth, was no longer able to decide to kill himself.
Therefore, Crown prosecutor Mark Tedeschi, QC, argued his death was not a suicide, but murder or manslaughter.
But the court also heard evidence from his sisters and a former friend, who said they had lucid conversations with him in the three months before his death.
Nine days into the trial, Justins changed her plea and admitted to aiding Mr Wylie's suicide, but Mr Tedeschi told the court he did not accept the plea and was going to pursue the other charges.
Euthanasia advocate Philip Nitschke gave evidence about a consultation with Mr Wylie, who had applied to have an assisted suicide in Switzerland.
But the Swiss organisation Dignitas rejected the application in December 2005, finding the evidence about his capacity was conflicting and it could not be certain he would qualify for an assisted suicide under Swiss law.
In February 2006, Dr Nitschke again met Justins and Jenning to discuss further options for Mr Wylie.
The court also heard that Mr Wylie's will - in Justins' favour - was changed a week before his death. Under an old will she stood to gain half of his $2.4 million estate, with the rest to be divided between his daughters