A carer and gambling addict murdered an elderly man by giving him a lethal dose of morphine and spent hundreds of thousands of dollars from the sale of his home on poker machines.
Justice Peter Hidden said Kerry Forrest probably crushed up the MS-Contin pain medication prescribed to her and mixed them in Bill Adamson's food in a Campbelltown motel between 13 and 16 April 2010.
She then attempted to have her GP certify Mr Adamson's death as being from natural causes and tried to have him cremated without his son or two sisters knowing he was dead.
On Tuesday, following a judge-alone trial, Justice Hidden found Ms Forrest guilty of murder.
"Ms Forrest misappropriated Mr Adamson's money and killed him to prevent that misappropriation being exposed," he said.
"She killed him by having him ingest MS-Contin. I cannot be certain how she did so but it is most likely that she crushed tablets and mixed them with his food."
Forrest, 54, a mother of two, had moved into Mr Adamson's Kareela home, in the Sutherland Shire, in the months after his wife Beryl died in September 2009.
Mr Adamson, a retired real estate agent, was reasonably fit for his age and mentally alert, and wanted Ms Forrest to help his market his invention, a water saving device known as the Rainsaver.
She soon took a keen interest in his financial affairs, including the $276,800 advanced to him under an equity release scheme for elderly people.
She negotiated the sale of his home for $690,000 on the condition $25,000 from the buyer's deposit would be immediately released.
Unbeknown to Mr Adamson, she promptly withdrew the $25,000, deposited it into her personal account and virtually spent it all within two weeks.
Mr Adamson believed the net proceeds of the sale of $318,822 would go towards building a house on a block of land Ms Forrest owned in Bundanoon and to raise funds to market the Rainsaver.
But Ms Forrest transferred hundreds of thousands of dollars into a series of other accounts and withdrew that cash so that by the end of April 2010, two weeks after settlement, the money was gone.
Records obtained from the clubs she frequented showed from July 2008 to January 2011, Forrest had lost $334,798.51 on the pokies. Of that, $136,458.66 was lost between 16 March 2010 - the day she withdrew the $25,000 deposit funds - and January 2011, the month before she was arrested.
The court was told she was a regular at Parramatta Leagues Club, Cronulla Sutherland Leagues Club, Campbelltown Catholic Club and the Wenty Leagues Club and became known to each of the gaming managers.
Forensic experts gave evidence that Mr Adamson would have been dead for up to 48 hours before Ms Forrest called 000 about 11pm on April 16, 2010.
He and Forrest had checked into the Maclin Lodge Motel at Campbelltown the previous Monday and planned to stay for a week.
Post mortem and toxicology reports showed the cause of death as morphine toxicity.
Eight months later, detectives found an empty MS-Contin blister pack inside Ms Adamson's briefcase and Forrest's DNA was found on it.
Justice Hidden said the Crown case was circumstantial. Crucially, Forrest did not contact Mr Adamson's son John nor his sisters Eva and Elizabeth to tell them of his death.
She told a funeral director Mr Adamson had no next of kin and when police subsequently told the director that he did have a son who would take over the funeral arrangements, Forrest lied and claimed John had told her he wanted nothing to do with it.
Justice Hidden said Forrest betrayed Mr Adamson's trust by deceiving him about the purpose of the sale of his home, withdrawing the money and using it for her own benefit.
He said she lied about her actions and whereabouts on the day of Mr Adamson's and created a sham note that suggested she believed he was alive when she left the motel room that morning.
He said she only called 000 after her GP refused to come to the motel.
"I am satisfied they were deliberate lies designed to cover up her involvement in the murder," Justice Hidden said.
Forrest sat hunched over in wheelchair while the verdict was read out.
A sentencing hearing will be held at a later date.