Andrew John Cobby is standing trial for murdering Gaylene Cobby - known as Kym - who was beaten and choked while taking out rubbish at her Gold Coast hinterland home on November 12, 2017.

He and Ms Cobby, 51, had been separated for many years at the time of her death outside the Worongary property he referred to as "the funny farm".

Cobby told an officer on the night of the attack he and Ms Cobby had received threats, with someone trying to extort money from them.

Ms Cobby was concerned someone was at the house and asked him to go there, Cobby told police, according to body-worn camera footage taken in an ambulance shown in the Brisbane Supreme Court on Thursday.

Cobby - who had been cautioned and read his rights by police - said his estranged wife "took the brunt" of the attack and he didn't have the strength to stop the assailant.

"I've laid over Kym trying to protect her," he said.

"I got hit in the back of the head, I think.

"It was an all-in brawl, an all-in fight."

Justice Peter Callaghan briefly adjourned the trial as Cobby appeared to become emotional while watching footage of himself sobbing and repeatedly saying he was sorry.

"I'm supposed to protect her, that's why she called me," he said.

Cobby was being taken to hospital after police found him at a property near to where Ms Cobby lived.

Detective Senior Constable Robert Wilkinson told the jury Cobby was in quite an "agitated state" when they found him.

He had a few abrasions, a couple of bruises and a black stain on his jeans.

The first paramedic on the scene Darrin Hatchman said it was clear when he arrived that Ms Cobby was dead.

He checked for a pulse, noticing bruising around her eyes indicative of a massive head injury, he told the court.

Ms Cobby's bloodied body was found about 11pm by her ex-brother-in-law Craig Eden near the road at the end of the long driveway of the house where they both lived, prosecutor Philip McCarthy said earlier.

At first Mr Eden - who had been married to Ms Cobby's sister - didn't recognise the mother-of-three.

"Kym Cobby had been choked, asphyxiated, and left for dead," Mr McCarthy added.

He said the jury would hear a locked red Chrysler Cobby borrowed from his flatmate that evening was found near the body.

The jurors would also hear audio from a neighbouring home's security camera of a woman start screaming about 11pm.

Mr McCarthy said the prosecution would suggest in the recording the woman could be heard screaming "Andrew, please", the screaming continued and it abruptly stopped.

"The Crown contend that the recording you will hear in this court room is of the last moments of Kym Cobby's life as she is killed," Mr McCarthy added.

Defence barrister Tony Kimmins said Cobby claimed the pair had been investing money with others, but there had been a falling out.

He told the jury Ms Cobby had complained she and family members had been threatened by people associated with the investments.

This included a report to police less than a month before she died.

He argued the jurors will have "great problems" in coming to the conclusion the prosecution established beyond reasonable doubt Cobby killed his estranged wife.

The jury is expected to hear from more than 50 witnesses over at least three weeks.

Australian Associated Press