A church-goer smothered a dying devout Christian with a pillow despite her victim's opposition to euthanasia, a court has heard.
Cancer patient David Paterson, 81, was close to a natural death when he was murdered by Heather Davidson, 54, in the bedroom of his care home on February 11.
About two hours before, she had called Macmillan Cancer Support to ask if smothering her friend would make her a murderer.
This was no mercy killing, and she acted "unilaterally" without thinking about what Mr Paterson wanted, or the views of family and staff, Teesside Crown Court heard.
Judge Simon Bourne-Arton will impose a minimum term on the mandatory life sentence when the hearing continues this afternoon.
Davidson had made complaints in the phone call to Macmillan about how the widower was being treated at Sowerby House, Thirsk, North Yorkshire, which the prosecution said were unfounded.
She wept in the dock as extracts from the call she made from her mobile phone during her final visit to Mr Paterson were played in court.
In the call, Davidson said her friend could not eat or drink, was "skin and bone" and was in a "dreaful state".
She told the charity's call handler: "It might be better if I could put a pillow over his head."
Later, she asked: "Would I be a murderer if I did that?"
The charity worker replied firmly: "In the eyes of the law, yes you would, yeah."
Davidson said in the call: "If he was a dog he would have been put down months ago."
In a macabre twist, the court heard Davidson has a previous conviction for trying to smother her neighbour's dog. After an argument, she took the pet and taped a plastic bag over its head.
The dog was found limp, hidden in a bedding box by a police officer, who managed to revive the animal.
The Macmillan call handler informed her supervisor during the conversation and the police were contacted but the call could not be traced immediately.
Davidson killed Mr Paterson despite knowing his religious beliefs, the court heard.
Jonathan Sharp, prosecuting, told the hearing: "As a devout Christian, he had strong ethical objections to euthanasia.
"He had said it will be God's decision, and only God's, when it was his time to meet his maker."
Davidson felt he was suffering, although Mr Sharp said the victim was "generally comfortable" and had been prescribed morphine.
Suspicions were raised immediately after Davidson alerted staff that Mr Paterson had died, as there was blood on the pillow. A post-mortem examination confirmed he had been smothered.
The defendant, from Sowerby, Thirsk, pleaded guilty to murder last month, after police discovered evidence from the calls she had made to Macmillan.
Mr Paterson was happily married for 51 years until his wife died in March 2014. They had no children, but he was in regular contact with his sister, nephews and nieces.
He was a "pillar of his local church", St Mary's in Thirsk, the court heard.
Mr Paterson and his killer got to know each other through a group for people with mental health issues, which she attended due to her problems with alcohol and where he was a volunteer helper.
She attended church with him and when he was in the home she visited two or three times a week.
The case continues this afternoon.