No DNA consistent with man killing wife

DNA evidence isn't consistent with Tony Thao Do murdering his wife in their Sydney home, but it does suggest the presence of another unknown man, a Supreme Court trial has heard.

Do has pleaded not guilty to the murder of his wife Kim Lien Huynh, 54, who died on September 13, 2012, from a combination of neck compression and sharp and blunt force injuries to her head.

During the trial on Friday, defence barrister Craig Smith SC said DNA evidence from the Cabramatta home where Ms Huynh's daughter found her dead supported what Do had told police.

"He didn't kill Kim. He loved Kim," Mr Smith told the jury on Friday.

"The DNA backs him up."

Swabs were taken from the right hand of Ms Huynh and tested for DNA.

Hits for at least three people, excluding Ms Huynh's daughter, were found, Mr Smith said.

But the major component, he said, didn't come from Do.

"It comes from an unknown male," he said.

He further argued that Do didn't have a motive and was so distraught by his wife's death he tried to kill himself.

"Why did you have to die, my dear," Do wrote in a message to Ms Huynh's spirit, Mr Smith said.

"Appear in the children's dreams and let them know."

It's been alleged Do, then 58, bludgeoned Ms Huynh before she died in their Cabramatta home between 7pm and 8pm.

Earlier, the trial heard he gave police two different accounts of what happened the day his wife was found dead.

Initially, he told police Ms Huynh had left their strata management business that afternoon while he had stayed at the shop.

He arrived at home soon after being called by his stepdaughter, the court heard.

A week later, he was released from hospital after trying to kill himself and said he had discovered his wife on the floor.

Thinking she had "fainted or fallen" he tried to pick her up, walking through blood as he did so, crown prosecutor Nicole Noman SC said.

Scared someone was still inside the house, he said he washed his hands and feet in the bathroom sink and then walked back to their shop and hid under a blanket.

The trial continues.