She thought she would find the pair hard at work chopping firewood.

But when Mrs Clements got to the back of the home, she found her husband Roger, 89, lying in a pool of blood next to a wood pile.

A bloodied axe was next to his body and her son David Clements, 50, was nowhere to be seen.

Mrs Clements ran to her neighbour's house to raise the alarm but by the time paramedics arrived, her husband was not able to be revived.

Police would later discover that her son had caught a taxi to his parents' house - in the suburb of Springvale - that day, telling the driver "I've got to use an axe today."

Sniffer dogs tracked David Clements' scent to the Wagga Wagga Country Golf Club, where staff said he asked them to call a taxi to take him to the train station.

The taxi driver told police he remembered Mr Clements because he had a dark, red stain on his pants about the size of a 20¢ coin.

Mr Clements then bought a CountryLink train ticket bound for Sydney.

When Cootamundra police finally found Mr Clements, he was sitting in a rail carriage chair drinking a can of beer.

He was arrested and charged with murder.

On Monday, just over a year since his arrest, Mr Clements was found not guilty of murder by reason of mental illness.

After acting Justice Jane Mathews handed down the verdict in the NSW Supreme Court, he waved to a number of family members who were sitting in court.

"This does not mean that he did not commit the physical act of murdering his father; it is clear that he did. But what is also clear is that, at the time he did so, he was mentally ill," acting Justice Mathews said.

He will remain in custody indefinitely but will be assessed by the Mental Health Tribunal every six months.

An agreed set of facts detailed how Mr Clements had been diagnosed with a form of schizophrenia in the early 1990s.

The facts also outline how he had fought with his father in the lead-up to the attack.

The evening before he killed his father, he spoke to his mother on the phone and said, "Tell Dad to get out of my head."

Roger Clements' death shocked the Wagga community, particularly those who lived in the affluent area of Springvale.

Mr Clements was a popular Wagga man who was the father of four children. He trained as a teacher at the then Wagga Wagga Teachers College in the 1950s.

Later, he contributed to the training of teachers with positions at Goulburn College of Advanced Education, which later became Charles Sturt University.

He was a talented rugby league player and a sprinter in his youth before becoming a keen lawn bowler in his later years.