Drug-induced psychosis led Hayden Kidd to kill his grandmother, court hears

A young man accused of murdering his grandmother with a garden tool was in a drug-induced psychosis and believed she was his abusive stepfather at the time, a jury has heard.

Hayden Kidd is on trial charged with the murder of his grandmother, Shirley Kidd.

A young man who hacked his grandmother to death with a gardening tool was in a cannabis-induced psychosis that led him to believe she was his abusive stepfather, a jury has been told.

Hayden Kidd, 22, faced the first day of his Supreme Court trial in Ballarat on Tuesday, accused of murdering his grandmother, Shirley Kidd, 67, with a mattock in the garage of the Darley home where they both lived.

In her opening address, crown prosecutor Erin Ramsay said two forensic psychiatrists found Hayden was in a cannabis-induced psychosis and experiencing delusions when he carried out the horrific attack that saw the tool lodged in the back of his grandmother’s skull.

Hayden told the psychiatrists that while in his psychotic state, he believed his grandmother was a former stepfather who had physically and emotionally abused him as a child.

“Both psychiatrists agree he was in an altered mental state,” Ms Ramsay said.

But the jury was told they disagreed on whether the attack was “conscious, voluntary and deliberate” or if Hayden had the ability to form an intention to kill, with their differing evidence to be of “great significance” to the trial.

Shirley Kidd was found dead in her Darley home. Picture: Facebook

The court heard Hayden had been living with his grandparents for about 18 months in the lead-up to the fatal incident, but was unemployed and spent most of his time in his bedroom which was a source of tension between them.

On the night of May 28, 2022, the jury was told Hayden’s then seven-year-old cousin, who was staying with the family, was sleeping in a bedroom with his grandmother, when Hayden entered the room and began choking him.

The boy later told police Hayden then took him to the garage and began opening the door, before he was confronted by Shirley who told him to put him down.

Hayden then began stabbing his grandmother with the mattock in front of his young cousin, investigators were told.

The jury was told the boy then got his grandfather, who was sleeping in a separate room, who went into the garage and discovered his wife of 43 years laying face down in a pool of blood with the mattock in the back of her head.

“It was clear to (the grandfather) she was dead,” Ms Ramsay said.

The court heard Hayden, who appeared pale and was struggling to keep his eyes open, then walked past his grandfather and said: “I’m going to sleep well tonight”.

Other family members and a friend were called to the home before Hayden, who appeared drug-affected, was arrested without incident.

Ms Ramsay said trace amounts of THC, which is found in cannabis, and an antidepressant were later found in his system.

Hayden later told the psychiatrists his memory of the attack was a blur but he at the time believed his cousin was a younger version of himself while his grandmother was an abusive former stepfather.

In his opening remarks, Hayden’s barrister Tim Marsh said it was not in dispute that his client killed his grandmother or that the incident was “tragic” or “awful”.

“The real issue is what was his mental state at the time when it occurred,” he said.

Wearing a maroon button-up shirt, Hayden was flanked by custody officers as he sat in the dock.

He at times closed his eyes as details of the fatal incident were described.

The trial, before Justice Michael Croucher, continues.