For more than two days, Crown prosecutor Brett Hatfield has been giving his closing address in the NSW Supreme Court in Natasha Beth Darcy's murder trial.

The 46-year-old Walcha woman denies sedating and gassing 42-year-old Mathew Dunbar, who was found dead on his 'Pandora' property in the Northern Tablelands town of Walcha on August 2, 2017.

Her guilty plea to aiding or abetting suicide was rejected by the Crown.

The Crown case is she tried to kill her partner more than once, knowing she would inherit his multi-million dollar farm, and left "a staged scene to conceal the fact this was murder".

On Friday, Mr Hatfield said she clearly showed no empathy for the deceased because she had been planning his murder for months, pointing to a police interview conducted shortly after.

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"Matt loves shopping. He's a great shopper. He's just so good and can always find bargains and it must be the gay in him," Mr Hatfield recalled her saying in the interview.

He asked the jury to consider the tone and manner of her interview, "how completely shallow emotionally, and completely lacking in empathy," she is.

"Less than 12 hours ago the man she claimed she loved was dead," Mr Hatfield told the court.

Her police interview was full of inconsistencies and lies she "made up on the run," including her reasons for walking into Mr Dunbar's bedroom on that deadly evening, Mr Hatfield claimed.

"On her evidence ... she goes to bed [on the couch] and then wakes up within minutes ... to put wood on the fire," he said.

Mr Hatfield said Darcy claimed smoke poured out from the fire and the smoke alarm went off, "then she goes to tell Matt what I done".

"Why you would tell someone who is apparently asleep that you turned the alarm off ... you wouldn't go wake them up to say you were worried you woke them up," he said.

Darcy's barrister previously cited a string of issues including the sheep farmer's confused sexuality, his serious leg problem and depression, as to reasons why he wanted to die by suicide.

But the last doctor to review Mr Dunbar's leg the day before he died said "he was extremely happy with his progress," and that his "outlook was positive."

This is in stark contrast to Darcy saying "the news wasn't great ... he would never be able to do exercise or anything like that again".

He also rejected Darcy's statement to police that she had "no idea" about the value of the property she stood to inherit, telling the jury she had no income, little wealth and knew very well the property was worth millions.

She also knew she was the sole beneficiary of the entire estate, he said.

The defence is yet to give its closing address to the jury. The trial continues.

- Australian Associated Press

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