A recent divorcee rammed his car into his former wife's new partner and then used an axe on the defenceless man in a frenzied assault, a jury has heard.
But jurors have been asked to consider the impact of Cambodian dictator Pol Pot's regime on Thanh Tran in deciding whether his axe attack amounts to murder or manslaughter.
Tran, then 75, attacked Pok Min Fah after the victim had dinner with Tran's adult children and former wife, and walked out of the former marital home in Cabramatta West on March 14, 2019.
The 59-year-old made it just a few doors before being knocked into a kerb by Tran's car.
An eyewitness is expected to tell the NSW Supreme Court jury he saw the car stop a few metres past Mr Fah and the driver go to the boot, pull out an object and walk to the fallen man.
Tran then struck Mr Fah "hard" numerous times, the Crown expects the witness to say.
A second eyewitness heard a bang, looked outside and saw Tran swing the axe "in a chopping motion multiple times at a fast pace with an angry look on his face".
After his arrest, Tran told police he didn't know the man he'd hit with his car, was attacked by the victim and then couldn't control his emotions.
Tran also denied talking to his daughter about Mr Fah.
But the Crown expects Nina Tran to testify her father told her Mr Fah was behind her parents' divorce.
"I expect Nina to tell you the accused told her the deceased was a bad person, that he'd ruined the family and that he was the reason for the divorce," the prosecutor told jurors on Monday.
During one phone conversation with her father, it was apparent the accused knew Mr Fah was visiting the marital home, though the daughter wasn't clear on how that was, the jury was told.
A small pair of binoculars were found on the car's passenger seat.
The severe injuries inflicted by Mr Tran were awful and it was hard to not feel "enormous sympathy" for the defenceless victim of the frenzied assault, Tran's lawyer told jurors.
"It might appear to you at first blush as a case of Mr Tran being a jealous ex-husband who couldn't deal with the divorce and separation from his family," Janet Manuell SC said.
"But is it so simple?"
Jurors would hear evidence of Tran's experiences with the Khmer Rouge, including becoming a forced labourer and witnessing atrocities.
"People who were close to him just disappeared," she said.
Tran escaped into Vietnam and then Thailand before coming to Australia in the mid-1980s.
Ms Manuell said Tran's traumatic experience didn't justify his killing of Mr Fah.
But at the close of the murder trial, she anticipated she would argue he was impacted by post-traumatic stress disorder and depression, the enormous losses in his life and his witnessing of "some of the worst atrocities imaginable".
Those factors could lead jurors to find Tran had a partial defence to murder due to an abnormality of his mind that left him unable to control himself at the time of the attack.
Tran has pleaded not guilty to murder but guilty to manslaughter.
The trial resumes on Tuesday.
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