A son, a staged crash, and a mother moved into the driver's seat — an inquest asks what the system missed

The car was driven in a straight line, at speed, into a tree.

Then, an Adelaide inquest was told this week, the man behind the wheel lifted his dead mother over his shoulder and placed her in the driver's seat.

Ethan Grosvenor, 27, and his mother Tracee Grosvenor, 58, crashed south of Adelaide on the night of December 3, 2022.

Tracee was killed. Her son took his own life 11 days later, while detained under South Australia's Mental Health Act.

Deputy State Coroner Naomi Kereru this week opened an inquest into both deaths — to determine whether the son killed his mother, and whether anyone could have stopped what came next.

Counsel assisting the coroner, Darren Evans, laid out a timeline that stopped making sense almost immediately.

Grosvenor, who lived with his mother, dropped his two children back to their mother late that evening.

He and Tracee left to drive home at 10.05pm.

The crash happened about ten minutes up the road. He did not call triple zero until 1.11am.

By the time paramedics arrived, Tracee's body was cold and rigor mortis had set in. She was in the driver's seat.

A witness told police they had seen the car pulled over near 10.30pm, with a "distressed" Tracee in the passenger seat.

DNA evidence later confirmed Grosvenor had been driving, and had moved his mother's body after the crash.

"Concerns about whether the collision was deliberate began to form, with reports of earlier violence being uncovered, and also reports of Mr Grosvenor having grabbed the steering wheel while his mother was driving," Evans said.

He was detained and admitted to Glenside Hospital.

What happened over the next eleven days is the second half of the inquest — and the part the family says the system got wrong.

Taken to the Adelaide Dental Hospital on December 9, Grosvenor vanished from the waiting room for ten minutes before returning, telling nurse consultant Jennifer Williams he had gone to "stretch his legs".

She told the court that had she believed it was a significant event, she would have reported it.

He was brought back on December 14 for further tooth pain. He asked to go to the toilet.

Shortly after, a doctor entering a stairwell saw him standing on a railing. He fell, and died of his injuries.

The court heard Grosvenor had been repeatedly detained, faced charges of violence against his mother, and was described as a man of rigid thinking who could not articulate his feelings.

"It seems likely that he had undiagnosed autism spectrum disorder," Evans said.

Outside court, Tracee's sister said police had never properly investigated, and only two nurses had been called to give evidence.

"We knew straight away it wasn't right — we were devastated," Julie Chapman said.

"The health system needs to listen to families."

"He was very disturbed. His mother did nothing but love him."

Kereru will hand down her findings at a later date.

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