Nurse Gibson Kariuki was sleeping off a night shift when something woke him.
"I heard screams … that gradually became louder from a woman. She was just screaming out of pain," Mr Kariuki told Christopher Cullen's murder trial in the NSW Supreme Court on Tuesday.
Mr Kariuki said the screaming, which seemed to be coming from the driveway area of his Sutherland apartment block, continued for about two or three minutes, before a car drove off.
"When I heard the car drive away, I thought maybe it was just domestic violence or something," he said.
Mr Cullen, 51, is on trial for the murder of his estranged wife Comrie, who was found with her throat cut in the car park of the St George and Sutherland Shire Anglers Club on January 22, 2014.
He has pleaded not guilty to her murder, but guilty to manslaughter on the basis of self-defence and provocation.
The trial has been told that earlier that morning, the couple appeared in court together over a dispute about a car registered under Mr Cullen's business name.
After the court made a ruling unfavourable to Mr Cullen, a car similar to his was seen at Ms Cullen's Sutherland unit block, where neighbours heard screaming and a woman saying 'Where are you taking me?', to which a man replied: 'Just wait in the car'.
Mr Cullen then went to a camping shop where he bought two fishing knives, labelled "guaranteed sharp", before driving to the fishing club around 1pm, the jury has been told.
The jury has been shown the knives, one of which has a 17 centimetre blade, as well as the shoes and two t-shirts Mr Cullen wore that day.
The court has been going through crime scene photos, including pictures of the Cullens' white Hyundai, which was found in the fishing club car park splattered with blood.
Ms Cullen's blood-stained handbag, containing broken sunglasses, was found in the boot, the court heard.
The court has previously been told Mr Cullen, who emerged from mangroves in Woolooware Bay in the hours after Ms Cullen's body was found, told police his estranged wife had "taunted" him about her sex life and that he "lost it".
Defence barrister Winston Terracini, SC, has told the jury they will hear medical and forensic evidence that could support Mr Cullen's further claims that his wife stabbed him, and he acted in self-defence, albeit excessively.
"He's saying that in the circumstances of this case, he behaved in an excessive way, and that he lost his self-control," Mr Terracini said.
The trial continues before Justice Ian Harrison.
