Woman's NSW grazier murder trial nears end

Natasha Darcy is on trial for the murder of Mathew Dunbar on his Northern Tablelands property.
Natasha Darcy is on trial for the murder of Mathew Dunbar on his Northern Tablelands property.

A NSW sheep farmer whose partner is accused of murdering him probably had a major depressive disorder, says an internationally recognised suicide expert called in her defence.

Natasha Beth Darcy, 46, has denied sedating and gassing Mathew Dunbar to inherit his $3.5 million property, contending he killed himself.

The 42-year-old farmer was found dead on his Pandora property in the Northern Tablelands town of Walcha on August 2, 2017.

The prosecution closed its case in the NSW Supreme Court on Tuesday, before the defence called Professor Matthew Large.

Under questioning from Darcy's barrister Janet Manuel SC, he said he had never spoken to Mr Dunbar but had gone through material such as medical records including his admission to a psychiatric unit after a suicide threat in June 2017.

A psychiatrist who saw Mr Dunbar testified in his view he didn't have a major depressive illness but possibly an adjustment disorder, and his condition related to Darcy's "emotional manipulation of him".

But Prof Large said he probably had a major depressive disorder of mild severity.

Asked about the absence of a suicide note, he said a minority of people who killed themselves leave a note.

Ms Manuel referred him to evidence of Mr Dunbar's interactions on the day before his death when he was described as being "completely normal".

"I don't think that is so rare," he said.

Referring to the "emotional manipulation" said to have been applied by Darcy, Prof Large said "I think it's tricky to form that view in a short period of time".

In the context of Mr Dunbar's depression "to sheet all of that home to a relationship issue in what seems to me to be a clear mental disorder is a pretty long bow".

He also was asked about Mr Dunbar's late adoptive father who was said to have suffered depression.

He rejected crown evidence that inheriting depression would not apply in this situation, saying major depression had a genetic and environmental component.

The Crown has previously referred to dozens of iPhone searches on Darcy's mobile phone including "99 undetectable poisons," "husband suspected of killing wife after stroke" and others relating to the bitterness and tastelessness of different mass murder pills.

Other searches included the phrase "how to commit murder".

Prosecutor Brett Hatfield is expected to begin the crown closing address on Wednesday.

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Australian Associated Press