A jealous divorcee spied on his wife's new partner with binoculars before deliberately running him down with his car and fatally chopping at his head with an axe, a jury has heard.
The elderly murder accused has given contradictory and confusing explanations to police and recently the NSW Supreme Court that should be rejected, crown prosecutor Katharine Jeffreys said in her closing address on Wednesday.
But Thanh Tran's disordered thinking and answers are a reflection of his suffering post-traumatic stress disorder and severe depression, his barrister Janet Manuell SC said in response.
There is no dispute that Tran, 79, from Cabramatta West, struck Pok Min Fah's head with the axe after hitting him with his car on March 14, 2019.
Tran has pleaded not guilty to murder but guilty to manslaughter, arguing 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.
Tran's depression was mild, according to some expert evidence.
And he was largely motivated by anger after his wife divorced him and began a new relationship with the 59-year-old, that "wrecked his marriage," and forced him to "start a new life," Ms Jeffreys said.
Married for more than three decades, the couple had a strained relationship and were in effect separated with his wife sharing their daughter's bedroom for the last 15 years they had together.
His daughter Nina Tran testified that he told her Mr Fah was a bad person and destroyed his family.
But Tran later said he held no ill feelings towards the new partner and remained "neutral".
He claimed self-defence to police saying first he was hit in the head, later his arm, while he told a psychologist Mr Fah appeared threatening,g carrying a ladder from his old home.
"If you are going to deliberately tell a lie why wouldn't you at least get your story straight?" Ms Manuell said, adding it showed a disordered mind.
While Mr Fah lay on the ground defenceless, Tran with force struck him more than 10 times at a fast pace looking angry, one witness wrote in a statement.
This caused bones inside his head to crack like an eggshell, and loosened parts of his fractured skull, amongst other severe injuries, the jury heard.
Tran said he kept the axe in his boot due to past attacks, while binoculars found on the front seat of his car were to "watch soccer matches" on fields far away.
The Crown rejected these assertions respectively as extraordinary and inherently implausible.
The picture of Tran sitting outside his former marital home "like a creepy old man ... looking through binoculars watching everything going on inside," was rejected by his lawyer as utterly baseless and devoid of any material evidence.
By the time Tran arrived in Australia his life was marked by unimaginable loss, trauma and grief, Ms Manuell said.
He grew up in Cambodia a few kilometres away from the Vietnam border and the ravages of war, and was later marched to various refugee camps, forced into labour from sunrise to sunset, and experienced "the disappearing" of about 16 family and friends, she said.
And Mr Fah holding a ladder from his old home, an embodiment of everything he had previously lost, was the "trigger" for his frenzied and brutal killing, she said.
"It was a cruel coincidence that he left when he did, carrying the ladder, and Mr Tran was sitting outside in a depressed state," Ms Manuell said.
The jury is expected to begin deliberating its verdict on Thursday.
