Homicide detectives are investigating whether a 19-year-old man arrested in connection with the death of an elderly man and the stabbing of a woman was related to the Perth couple.
Police were called to Mattison Way in Greenwood about 8am on Monday, following reports a man had been seriously injured.
An 81-year-old man and 75-year-old woman were found with “serious injuries”.
The man died at the scene, while the woman was taken to Royal Perth Hospital where it is understood she remains in a stable condition.
Residents in the Greenwood area received a message from WA Police warning them of the unfolding situation and urging them to stay indoors while they hunted for the alleged knifeman.
“WA Police are attending a serious incident in the Greenwood area. Members of the public should be alert, not alarmed,” the message read.
“Please stay indoors and limit your travel. Suspicious activity can be reported to police via triple-zero.”
Police air wing, the canine unit, local police and detectives were deployed to the quiet residential area.
About 9.20am, police apprehended a 19-year-old man on Forest Hill Drive in neighbouring Kingsley.
Detective Inspector Gary Butler said police understood the parties were “known to each other in some way”.
“Homicide Squad detectives are in the early stages of their investigation. However, early indications suggest the parties were known to each other in some way,” he said on Monday.
“We believe the man in custody may be linked to a family member.”
Mr Butler confirmed the family dog, who had come to its owners’ aid, was also stabbed during the alleged attack.
A Kingsley resident recalled the moment the alleged offender was apprehended by police.
“We looked outside and there was a whole bunch of police cars with the man face down, handcuffed behind his back, on the top of our driveway,” Nicky Haynes told the West Australian.
“It’s terrible and for them to catch him on our driveway — it’s not it’s what happens in the suburb … it’s a bit scary.”
Another onlooker said the man didn’t “put up a fight” when police arrested him.
“The first thing I heard was a police officer yell ‘get to the ground, get to the ground’ — I’m guessing he had his firearm drawn at him as the officer was only by himself,” he said.
“The guy laid down straight away, he didn’t put up a fight, he didn’t try to run or anything like that.”
“He got him on the ground straight away, pinned him there, then there was cop car after cop car after cop car.
“He was just a young guy … wearing socks and slides and a bum bag.
“He just looked really young, almost 15. He didn’t say much — only when the cops initially got him on the floor he was yelling, but then he didn’t say a word after that.”
It is understood charges have not yet been laid.