NSW woman denies killing farmer boyfriend with sedatives blended in Nutribullet

A woman accused of killing her sheep farmer boyfriend months after she became the sole beneficiary of his estate has pleaded not guilty to his murder.

Natasha Beth Darcy, 44, is accused of murdering grazier Mathew Dunbar, 42, on his multi-million-dollar Merino property 'Pandora' in the NSW country town of Walcha on August 2, 2017.

It's alleged she blended a cocktail of sedatives in a Nutri-Bullet before gassing Mr Dunbar, a court has previously heard.

Today Darcy appeared on a video screen in the NSW Supreme Court from Mary Wade Correctional Centre in Lidcombe and said "not guilty, your honour" when asked if she had killed Mr Dunbar.

Justice Elizabeth Fullerton then ordered her trial to begin on June 1 next year, estimating it would run for six to eight weeks.

During a bail application earlier this year, a court heard Darcy had previously set fire to a house where her paramedic ex-husband Colin Crossman was sleeping in 2012.

The Crown argued in the lead up to Mr Dunbar's death, Darcy had Googled and deleted a number of internet searches including; "Does helium show up in an autopsy", "Suicide bag", "Euthanasia device", and "Helium filled exit bag".

It's the Crown case she used a false name to purchase ram sedatives from an Armidale vet, which were used to drug Mr Dunbar.

She is then accused of wrapping a plastic bag around his head and placing a tube connected to a helium tank underneath it.

During the hearing, her lawyer told the court Mr Dunbar had committed suicide and said he had spent time in a mental health facility two months before his death, after allegedly threatening to end his life.

Justice Stephen Campbell refused Darcy bail in January stating; "I am convinced that this is a strong crown circumstantial case".

Mr Dunbar's heartbroken mother Janet still struggles to comprehend the loss of her son.

"He'd give you the shirt off his own back and unfortunately he was too trusting," Ms Dunbar told 9News.

"He just wanted to belong to a family. Family meant everything to him," she said.

Mr Dunbar's neighbour and close friend Bill Heazlett said he was still very much missed.

"It's a loss to us all, a loss to the community and a loss to us particularly as friends," he said.

Readers seeking support and information about suicide prevention can contact Lifeline on 13 11 14. National Domestic Violence Service: 1800 RESPECT (1800 737 732). If you are in immediate danger call Triple Zero (000).