A mother and son who deliberately ran down a teen with a ute and left him to die in a cold-blooded revenge killing have been jailed for more than two decades.

Jayden Walmsley-Hume, 21, and his mother Katie Walmsley, 40, saw Taj Hart walking on the side of the road in Nowra on NSW south coast in February 2022.

Walmsley-Hume deliberately steered the white dual-cab towards the 18-year-old, mounted the curb and struck the teen, pulling him underneath the vehicle.

A NSW Supreme Court jury found the mother and son guilty of murdering Hart in August 2024.

In sentencing today, Justice Robertson Wright said the pair were on the lookout for an opportunity to allow Walmsley-Hume to exact the revenge they wanted.

Hart was hit from behind and did not have an opportunity to defend himself or get out of the way, he said.

“The actions which led to his death were cowardly and done in cold blood,” he said.

“He was effectively helpless.”

The court was told Hart and Walmsley-Hume had a history of disputes in the four years preceding the incident, including one altercation that left the killer’s elbow badly fractured.

Walmsley-Hume told Hart something like “you’re dead” or “you’re gone” after he sustained the injury, Justice Wright said.

“I do not accept that such a comment amounted to only mere words,” he said.

Katie Walmsley’s animosity towards Hart had also escalated significantly after her son was injured, Justice Wright found.

The duo were on the run until their arrest on April 7, 2022.

Katie Walmsley helped her son clean out the ute and used fake names to arrange accommodation in various hotels, motels and caravan parks for weeks after the murder to evade detection.

Walmsley-Hume initially blamed the vehicle damage on hitting a kangaroo before arguing at trial he killed Hart, but that wasn’t his intention.

Justice Wright found beyond reasonable doubt the driver intended to kill Hart.

Walmsley-Hume’s young age and drug abuse – including injecting ice and heroin with his father from the age of 13 – were taken into account on sentence.

Katie Walmsley also experienced hardship as a child, and raised her son as a single parent while caring for her uncles and grandparents after they became ill, Justice Wright said.

Hart’s family and friends filled the courtroom, wearing matching T-shirts printed with his photo.

“Hart was described as a person who had a bright future ahead of him, all brutally cut short,” Justice Wright said.

“There is nothing a sentencing court can do the to undo the harm caused by a murder such as this.”

He sentenced Walmsley-Hume to 23 years and six months in prison, with a non-parole period of 16 years.

His mother was sentenced to 21 years and six months, and a non-parole period of 15 years.