An elderly Sydney divorcee who ran down his romantic rival before hacking him to death with an axe has been jailed for at least 15 years.
"One must infer that the final ordeal of the deceased must have been excruciatingly painful and terrifying, although mercifully short," Justice Robert Button said on Friday.
"And one can also infer that the loss to the former wife of the offender of the man with whom she was shortly to commence a new romantic life in such circumstances has been exceptionally distressing."
Thanh Tran was found guilty in October of murdering 59-year-old Pok Min Fah on March 14, 2019, outside his ex-wife's Cabramatta West home.
The now 79-year-old, who had no criminal history, didn't deny repeatedly striking him with the axe after hitting him with his car.
But he unsuccessfully argued his judgment was substantially impaired due to a loss of control caused by trauma from his lived experience of Cambodian dictator Pol Pot's regime.
In the NSW Supreme Court on Friday, Justice Button jailed him for 20 years with a non-parole period of 15 years, saying the sentence will almost certainly lead to him either dying in jail or being released in a state of enfeeblement.
"But that is the inevitable consequence of what Mr Tran has done, and the stage of his life at which he has done it," he said.
Tran and his former wife had only recently divorced, but the intimate side of their marriage had ended two decades previously.
She was in a new relationship with Mr Fah and they were to move in together days after he was killed.
Tran had moved out of the Cabramatta family home months earlier and was living in lonely and isolated circumstances in a nearby small apartment.
"He maintained a great fondness for his daughter, and had asked her to move in with him, an invitation that she had declined," the judge said.
Tran was sitting in his car outside the family home when he saw Mr Fah walk out carrying a metal ladder Tran had not taken with him when he moved out.
Tran drove his car directly at Mr Fah, knocking him to the ground, before calmly stopping and obtaining the axe from the boot.
While his defenceless victim lay on the ground, he repeatedly hit his head with the axe.
"To express things plainly, the deceased was hacked to death where he lay."
The judge rejected claims Tran had binoculars in the car because he sometimes used them to watch soccer games from a distance and that he had the axe for self-protection.
He set out Tran's terrible experiences in Cambodia and Vietnam, where he had endured a life that featured great deprivation on many occasions and for a time "gross inhumanity".
He accepted that Tran was suffering a mild version of major depression and that his life had been damaged by post-traumatic stress disorder, founded upon all of the grossly adverse experiences that he had endured.
"The loss of family life in late 2018 and early 2019 was, I accept, yet another loss, one which the offender by then was incapable of bearing."
If he became eligible for release to parole, his prospects of rehabilitation would be excellent but the judge noted he had expressed no remorse whatsoever.
"It is noteworthy that he has not even seen fit to express remorse for the unquestionable suffering that he has visited upon his former wife, and also upon his beloved daughter, who was in the habit of referring to the deceased as 'uncle'."
