A elderly woman’s level of dementia meant she would have been unable to comply with orders barked at her by a police officer before being fatally tasered, a court has been told.

Senior Constable Kristian James Samuel White shot his stun gun at great-grandmother Clare Nowland at the Yallambee Lodge aged-care home in the southern NSW town of Cooma in the early hours of May 17, 2023.

The 95-year-old hit her head on the floor when she fell and had an inoperable bleed on the brain, dying at Cooma Hospital a week later.

White, who says he acted lawfully under his duties as a police officer, returned to his NSW Supreme Court trial on Wednesday.

Geriatrician Susan Kurrle told the jury she diagnosed Mrs Nowland with moderate to moderately severe dementia at the time she was tasered.

While still mobile thanks to her four-wheeled walker, the 95-year-old would have been unable to understand what was happening around her or comply with instructions, she said.

In video footage played on Tuesday, White could be seen shouting orders at Mrs Nowland as she shuffled forward while gripping both a steak knife and her walker from within one of the facility’s treatment rooms.

“You keep coming, you’re going to get tased,” the officer told her before he fired.

Professor Kurrle said Mrs Nowland’s behaviour had escalated in the three months before her death.

“She was constantly resistant to any changes or anything they asked her to do and she didn’t appear to understand,” the expert said.

“With hindsight, it’s very clear that the symptoms and signs were developing over that time.”

Mrs Nowland exhibited anti-social behaviour in early 2023, including taking residents’ food, trying to undress in social areas, disturbing residents in their rooms, wandering around in the cold and dark, and refusing to accept staff assistance, the jury heard.

The court was played CCTV footage of three incidents at Yallambee Lodge in March and April 2023, when the 95-year-old physically lashed out, rammed one staff member with her walker, and climbed an embankment and got stuck in a tree.

She was admitted to hospital on April 16 and was prescribed the anti-psychotic drug Risperdal to calm her aggressive behaviour after punching and biting staff.

She was settled with some rosary beads and tea after the incident.

Under questioning by defence barrister Troy Edwards SC, Prof Kurrle admitted Mrs Nowland’s behaviour in the moments before she was tasered could have resulted from staff deciding to reduce the dosage of Risperdal two days prior.

Registered nurse Caroline Baker worked at Yallambee Lodge for just over two weeks and was on duty when White was called to the aged-care home.

She tried to get Mrs Nowland out of three other residents’ rooms about 3am on the day of the incident after the great-grandmother grabbed two steak knives and a jug of prunes from a kitchen, the court was told.

Ms Baker said nothing unusual had been raised about the 95-year-old at handover when she started her shift.

The trial continues.