A jury found Natasha Beth Darcy guilty of murder on Tuesday morning in the NSW Supreme Court in Sydney.

The panel of 11 jury members returned their verdict just before midday, after deliberating since Wednesday morning last week.

Darcy had pleaded not guilty to murdering Mathew Dunbar, who was found dead in his bed on his Pandora farm in Walcha on August 2, 2017.

It came after a 10 week trial that heard from multiple witnesses.

Darcy will now face a sentencing hearing in October.

Darcy, aged 46, denied giving Mr Dunbar a drug-filled blended drink and then gassing him in bed before his death.

Crown prosecutor Brett Hatfield submitted Darcy started looking for ways to murder the Walcha farmer by poison in February 2017, citing searches on her iPhone and on a MAC computer.

It was the Crown case that Darcy tried to kill her de-facto partner more than once knowing full well she would inherit his multi-million dollar farm, and left "a staged scene to conceal the fact this was murder".

The Crown maintained the accused staged evidence to make the death look like a suicide, and told lies to distance herself from some of the evidence, or several searches made on iPhones and other devices on poisoning, drugs, and autopsies.

The Crown also claimed Darcy offered a friend $20,000 to get her to lie in court in her case and had made a joke about burying a body.

The Crown submitted evidence to show Mr Dunbar wanted love and a family but what he got was "a cold and calculating person who was determined to inherit his wealth".

In her closing address, defence barrister Janet Manuell SC submitted 12 distinct reasons to the jury that the Crown had not excluded that Mr Dunbar died by his own hand.

Ms Manuell submitted that a lot of lies were told by the accused, and it was part of their case that "once you tell a lie, you have to tell a lot more lies" to make up the initial one.

Ms Manuell told the jury that people tell lies for all reasons.

She also said the defence case was that if the jury believed that there was any "reasonable possibility that he died of his own hand, then you must acquit the accused".

The defence maintained Mr Dunbar was a very generous person who gave gifts unasked to people, but there was no evidence of spending on luxurious items like jewellery, bags, and overseas trips for Darcy.

Ms Manuell said the defence maintained there was no evidence of a sexual relationship but Darcy and Mr Dunbar slept in the same bed, and she made the house homely, and took Mr Dunbar to various medical appointments.

She also carried out routine jobs and chores on the farm, like a normal family.

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