A man who fatally mowed down Taj Hart with his ute did so to start a fight with the teenager but not kill him, a jury has heard as they prepare to begin deliberations in the murder trial.
Jayden Walmsley-Hume, 20, and his mother Katie Walmsley, 40, pleaded not guilty to murdering Taj Hart, 18, as he walked along a road in Nowra on the NSW south coast on February 24, 2022.
The pair have faced a joint three-week trial in the NSW Supreme Court in Wollongong, where a jury is due to retire shortly to deliberate on a verdict.
Walmsley-Hume's barrister Sharyn Hall SC on Thursday said it was not in dispute her client killed Mr Hart.
"He hit Taj Hart and he took Taj Hart's life in doing that," she said.
But Ms Hall added that after hearing direct evidence from Walmsley-Hume the jury should conclude he was someone who made decisions on the spur of the moment.
"This is not to say he didn't give things any thought, but it was a reasonably simplistic level of thinking," she said.
On that basis, she said there was not enough evidence to support the murder charge because he did not either intend to kill or cause serious bodily harm to Mr Hart.
"There can be no doubt that what Mr Walmsey-Hume did was unlawful; there can be no doubt that it was dangerous," Ms Hall said.
"Murder, members of the jury, it was not."
Crown prosecutor Kate Ratcliffe earlier argued Walmsley-Hume drove at Mr Hart with murderous intent and that his mother, as a passenger in the vehicle, was part of a joint agreement to commit the crime.
Walmsley-Hume had a background of conflict with Hart and the pair had been involved in a number of altercations, including one in which the alleged killer's elbow was badly fractured, the jury heard previously.
"(The murder) occurred after a build-up of extreme animosity and violent conduct by both accused towards Mr Hart and his mates," Ms Ratcliffe earlier said.
Ms Hall agreed that the history of violence between the pair was on Walmsley-Hume's mind, but she argued he had struck Mr Hart only "to call on a confrontation, bring on a fight".
Katie Walmsley's barrister Edward Anderson told the jury there was also insufficient evidence about his client's state of mind at the time to convict her of murder.
The jury would have to accept she agreed the pair should drive the ute into Mr Hart in order to kill him or cause him serious injury, he said.
"Knowing this was going to occur on a busy street, at three o'clock in the afternoon, in front of countless witnesses, in a car registered to her son," he said.
Mr Anderson said it was more likely Walmsley-Hume acted on his own, doing "something beyond foolish, impulsive" and unexpected by his mother.
The trial continues.
