Peter Nguyen-Ha, 34, is on trial in the WA Supreme Court accused of murdering Ralph Matthews Cox in what prosecutors claim was a "drug deal gone wrong".(Supplied: Anne Barnetson)
Peter Nguyen-Ha is on trial in the WA Supreme Court charged with murdering Ralph Matthews Cox at his Landsdale home in January 2022.
Mr Matthews Cox was shot dead through the bedroom window of his home.
Mr Nguyen-Ha, taking the stand to give evidence in his defence, says he only fired non-lethal rounds at the home.
A Perth man accused of shooting a man dead through his bedroom window has claimed he only fired non-lethal rounds at the house.
Peter Nguyen-Ha has told his murder trial in the WA Supreme Court another man fired the fatal shot at the Landsdale home.
Mr Nguyen-Ha is on trial, accused of murdering Ralph Matthews Cox in January 2022.
The court has heard Mr Nguyen-Ha went to the house with a shotgun, looking for a man who had stolen tens of thousands of dollars from him in a "fake" drug deal.
But the man who died, Ralph Matthews Cox, had no knowledge of that incident and no involvement in crime.
Ralph Matthews Cox was shot dead in his own bedroom in suburban Perth, in a case of mistaken identity, by a drug dealer seeking revenge, a murder trial is told.
Mr Nguyen-Ha, taking the stand to give evidence in his defence, said he fired a pump-action shotgun twice at the window, using salt rounds.
"Fired a shot and started moving to the left," he said, before firing a second shot.
It was at that moment, he told the court, "a flame came past me" and he heard "a bang".
The 35-year-old said he saw the middle window of the house smash and "I looked back, I seen Matty".
Mr Nguyen-Ha said "Matty" was holding a double-barrelled shotgun.
"I had no idea that Matty had his own gun," Mr Nguyen-Ha said.
Matthew Gempton, who was a drug debt collector, has admitted driving them to the scene but denied firing any guns.
Peter Nguyen-Ha said Gempton handed him a pump-action shotgun on the way to the Landsdale shooting, and afterwards, told him to keep it.
Bullet holes in the bedroom window of a house in Landsdale, where Ralph Matthews Cox was fatally shot.(Supplied: Supreme Court of Western Australia)
"That's yours now, you used it, it's your responsibility," Mr Nguyen-Ha said Gempton told him in the car as they left Landsdale.
Mr Nguyen-Ha told the court he'd been pressured by Gempton to target the house but he did not want to fire live rounds.
So before they arrived at the Landsdale address, he had cut open the shotgun rounds and replaced the pellets with rock salt.
He told the court that he found out later that someone had died in the shooting and questioned Gempton.
"Why did you fire live rounds the way you did?" he said he asked him.
The court has seen body-worn camera footage of Peter Nguyen-Ha being arrested at Burswood days after the shooting, when a shotgun was found in his car.
Police body camera footage shows what police say are cartridges and a firearm at the scene of the arrest.
Mr Nguyen-Ha told the court this was the shotgun Gempton gave him, which was used at Landsdale.
The 35-year-old admitted he had fallen asleep at the wheel after he had "taken meth".
The car had hit a wooden bollard.
Mr Nguyen-Ha told the court he'd been selling drugs "every day" since November 2021, and had been convicted of drug offences in the past.
He said he did not co-operate with police after his arrest because he did not want to get in trouble for selling drugs, but also did not want to "snitch" because he thought it was wrong.
"I didn't want to get mixed up with what Matty did," he said.
Forensics officers scour the scene after the shooting death of Ralph Matthews Cox.(ABC News)
"Because that's a very serious matter.
Gempton,who has pleaded guilty to manslaughter, had himself told the court earlier in the trial he did not use a gun on the night.
He had said Mr Nguyen-Ha fired at the house three times.
The court has been told Gempton received a reduced sentence in return for giving full and truthful evidence at Peter Nguyen-Ha's trial.