A police officer who fatally tasered a 95-year-old with dementia symptoms could face a lengthy stint in jail after a jury found him guilty of her unlawful killing.

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

In video footage played at his NSW Supreme Court trial, the 34-year-old officer was heard saying “nah, bugger it” before shooting the great-grandmother in the torso.

Mrs Nowland, who was holding a steak knife at the time, fell backwards and hit her head before dying a week later in hospital.

After hearing evidence and submissions over the eight-day trial, the 12-person jury returned with a guilty verdict of manslaughter on Wednesday.

They had been deliberating for 20 hours.

Crown prosecutor Brett Hatfield SC successfully argued White was criminally negligent or conducted an unlawful and dangerous act by firing the Taser in a move which was “utterly unnecessary”.

In reaching its verdict, the jury rejected arguments by defence counsel Troy Edwards SC that the 34-year-old officer’s use of the Taser was a proportionate response to the threat that Mrs Nowland posed.