Rian Strathdee was just six years old when a truck driven by Allan Michael slammed into the back of his family's Suburu, shortly after 9.30pm on November 26, 2004, killing him and seriously injuring others in the car.
Dyson did not stop after the accident on the Hume Highway southwest of Sydney, instead fleeing to Queensland where he was not tracked down by investigators until 2022, nearly two decades later.
The truck did not stop after slamming into the family's car, killing six-year-old Rian Strathdee (Scott Webster/AAP PHOTOS)
Rian's mother, Jasmine Payget told a sentence hearing in the NSW District Court on Friday that Dyson's decision not to stop robbed her family of closure.
"Being in the purgatory that we have been, could have ended a long time ago," she said.
In August, a jury found Dyson guilty on one count of dangerous driving occasioning death and two counts of dangerous driving occasioning grievous bodily harm.
Ms Payget said before the crash she was a happy young mother of two boys and was halfway through reading the Harry Potter books to Rian.
"At the end of their day my younger son was dead, my oldest son was severely injured in hospital, my husband in a different hospital with a broken neck," Ms Payget said.
"I was utterly devastated, in shock and disbelief."
Ms Payget described hit-run crimes as "particularly cruel" for victims, saying it had added layers to her family's distress.
"The hit-run made it impossible to have a sense of what happened," Ms Payget told the court.
"It messed up our family, because there was always an unfinished part up to this terrible story."
Jasmine Payget, with Laurie Strathdee, said the hit-run had messed up her family. (HANDOUT/STRATHDEE FAMILY)
Crown prosecutor Nerissa Keay questioned whether Dyson had ever fully accepted responsibility for the crash and come to terms with the damage he caused.
"The offender knew that he had collided with the Subaru," Ms Keay said.
"It does not matter that it wouldn't have changed the outcome if Mr Dyson had stopped and assisted.
"It's part of assisting in the investigation, as well as providing assistance to people who are killed or injured and to respect their dignity."
Defence barrister Harry Maarraoui said it was conceded the crash resulted from more than a moment of inattention by Dyson, but said it was "not far from it".
During the trial, Dyson's legal counsel had tried to shift the blame for the collision onto Ms Payget, who was driving the Subaru.
It was suggested she was driving too slowly and had failed to properly check her mirrors before pulling out onto the highway, an argument the jury ultimately rejected.
Judge Ross Hudson is due to deliver a sentence on November 22.
