A Perth teenager who laid in wait behind a wall before throwing a concrete block that fatally injured a pregnant mother is set to be sentenced.

April 28, 2023

A Perth teenager who hurled a concrete block at a car and fatally injuring a pregnant mother was “laying in wait” behind a wall for the vehicle, a court has been told.

Diane Miller, 30, died in hospital, along with her unborn child, several days after a brick thrown by 17-year-old boy hit her in the head at a shopping centre on November 29 last year.

Perth Children’s Court on Thursday heard the incident followed a heated verbal altercation with weapons in a car park involving Ms Miller’s partner, the teen and a group of his friends.

Prosecutor Clare Cullen said the boy, who cannot be named for legal reasons, had been “laying in wait” behind a wall before hurling the 1.9-kilogram brick at the car as it drove away from the scene of the stoush.

“The concrete went through the window striking Ms Miller to the head,” she said.

“It was cowardly.”

The teen, who was initially charged with murder before agreeing to plead guilty to the lesser charge of manslaughter, fled the scene before handing himself in to police several hours later.

His lawyer, Kate Turtley-Chappel, said the boy “was fearing his and other’s safety” when he threw the brick.

“(The defendant) threw the rock without thinking and ultimately it ended in the loss of human life,” she said.

“He is quite frank in saying he wasn’t thinking in terms of the outcome.”

Ms Turtley-Chappel said the teen was extremely remorseful and had accepted he would be sentenced to a term of imprisonment.

“This is a young person who says ‘I want to be here (and) I did wrong and I need to do my time’,” she said.

“He sits in this courtroom accepting his fate and knowing he caused so much devastation.”

The hearing continues on Friday when the teenager is expected to be sentenced.