Cy Walsh stabbed father Phil 20 times

Meredith Walsh will go on loving her son, even though his actions broke her heart.

Cy Walsh fatally stabbed his father, former Adelaide AFL coach Phil Walsh, 20 times in a schizophrenic episode at the family home.

But on Wednesday he was found not guilty of murder because he was deemed to be mentally incompetent at the time in July, 2015.

The 27-year-old will now spend his life under psychiatric supervision.

Phil Walsh, 55, was stabbed in his bed with a hunting knife, court documents reveal.

His wife Meredith says not enough was known about their son's mental illness.

"My heart remains broken," she said in a statement read to the Supreme Court in Adelaide.

"My daughter is also shattered."

But she will not abandon him.

"I will continue to love and support my son as his father has always done."

Court documents reveal he had struggled for years with mental health problems, which started in 2011 as he was backpacking around the world.

He had heard voices he believed were from another dimension. He had felt there was a demonic force pressing on him.

He had at times believed his father was the devil.

Walsh once bought a length of rope during a bout of severe depression but didn't use it.

He had been admitted to psychiatric hospital several times, once after a fist fight with his father. But he was later released and returned to university.

He also had a history of extensive drug-taking and used magic mushrooms and cannabis.

He was aware he had mental health issues but he chose to continue to self-medicate.

Shortly before his death, Phil Walsh received a chilling text message from his son.

"It is your duty to pump up your troops," it said.

"But honesty is the key.

"War needs to be a thrill.

"If Phil Walsh should fall ... the Crows will experience many years of darkness.

"Please focus on hope ... and remember to put your family before yourself."

Ms Walsh said there was a lack of information available to families like hers, calling for increased mental health research and awareness.

"We now all live with the devastating consequences of a mental illness that was not understood," she said.

One psychologist in the case believed Walsh had been unwell for far longer than those around him realised and that his use of drugs masked this.

Justice Anne Bampton accepted the diagnosis of schizophrenia that three medical reports had come to following Walsh's arrest.

"I find he was suffering a psychotic episode as a result of schizophrenia, which at the time of the conduct was undiagnosed and untreated," she said.

But Walsh was not affected by drugs at the time, she found, accepting forensic reports.

Walsh wore a white shirt with a light-blue tie, and his dark hair was brushed back when he appeared in court by video link.

Justice Bampton fixed a term of supervision equivalent to life imprisonment.

The Adelaide Football Club chose not to comment.