A Perth teen who lay in wait behind a wall before throwing a concrete block that fatally injured a pregnant mother will serve five years in detention.

April 28, 2023

A Perth teenager who hurled a concrete block at a car, fatally injuring a pregnant mother has been sentenced to five years in detention but with time served could be released in less than two years.

Noongar woman Diane Miller’s family screamed out in grief and anger in court over the sentence handed down on Friday.

The 17-year-old boy, who cannot be named for legal reasons, pleaded guilty to unlawfully killing Ms Miller, 30, in December last year.

He admitted lying in wait behind a wall after a car park melee involving weapons on November 29 and throwing a 1.9 kilogram brick at a car.

It flew through the passenger side window and hit Ms Miller, who was five months’ pregnant, in the head, causing catastrophic injuries.

She died in hospital, along with her unborn child, amid an outpouring of anguish in the Noongar community.

The teen, who was initially charged with murder before agreeing to plead guilty to the lesser offence of manslaughter, fled before handing himself in to police shortly after.

Ms Miller’s family wept and vented their anger in Perth Children’s Court as Judge Hylton Quail read the facts of the “tragic” incident.

“You were impulsive … You didn’t stop to think if it was a bad idea,” he told the boy.

“You persisted with the plan to use the rock.”

Judge Quail said the boy’s traumatic life and brain damage contributed to his decision to throw the lump of concrete.

He also accepted the teen was genuinely remorseful and co-operated with police.

However he said Ms Miller was an innocent and blameless victim of a cowardly act.

“Most significantly she had a baby and was 20 weeks’ pregnant,” Judge Quail said.

“You took her life and deprived baby Lloyd of his mother and you deprived Ms Miller’s unborn child of life.

“You will have to live with the consequences for the rest of your life.”

Judge Quail read Ms Miller’s mother, Annette Miller’s, victim impact statement to the court.

She said her daughter, affectionately known as “Dinosaur” by family, was her pride and joy.

“I had to grieve twice as much because I not only lost my daughter but also my unborn grandchild,” she said.

Judge Quail sentenced the boy to five years’ detention at Banksia Hill Juvenile Detention Centre and he must serve a minimum 26 months before applying for supervised release.

With time served he could be released in about 21 months or opt to be transferred to an adult facility when he turns 18

Judge Quail acknowledged the difficulties the teen had faced in the facility and would continue to endure including unlawful 20-hour lockdowns due to staff shortages, and threats from other inmates.

He also said he had witnessed a member of Ms Miller’s family threaten the boy in court on Thursday during sentencing submission.

After the sentence was handed down Ms Miller’s family’s anger boiled over as they were ushered away by security.

Outside, Ms Miller’s brother Malcolm Clifton said he was outraged by the sentence and the teenager should have also been punished for the death of his sister’s unborn child.

“There’s justice for you, what a load of bulls*** … I’m sick to the guts with the law system … He should have got 15 so he can think about what he’s done,” he said.

“He knew what he was doing when he picked up the brick. Everyone knows what they are doing when they pick up a weapon. They intend to use the f***ing thing.”

Ms Miller’s sister, Alison Miller, described her as a beautiful soul.

“She was harmless … Everyone has got to fight this,” she said.