Mark James Bombara, 63, shot dead Jennifer Petelczyc, 59, and her daughter, 18-year-old Gretl, at their Perth home on May 24, 2024, before killing himself.
An inquest into the deaths has heard Bombara was searching for his estranged wife Rowena, who he had separated from a month earlier, but she wasn't at the home.
Jennifer called Rowena, who was with her daughter Ariel, and they heard the shooting unfold, prompting Ariel to call triple zero while her mother was still on the call.
"There's shots, there's shots," Ariel told the Western Australia police operator in the call, which was played to the WA Coroner's Court on Thursday.
"(Jenny is) my mum's best friend and my dad had shown up at there with a gun."
Screams and crying can be heard during the call.
"She said put the gun down and then we heard gun shots," Ariel said.
"Two shots.
"Mark Bombara, my father, has a gun."
Despite being told Bombara was in the home with a weapon and shots had been fired, the operator did not trigger a priority one incident for life-threatening emergencies
He triggered a lower-level priority two report for urgent incidents involving serious risk.
"I believe the judgment to make it a priority two was incorrect," WA police commander Jason Longhorn said.
Bombara fired five shots, all told.Â
The last took his own life after police arrived, counsel assisting the coroner, Rachael Young, said in her opening remarks.
Bombara had become fixated on his failed marriage and believed Ariel had orchestrated the split with Rowena.
Ariel told the triple-zero operator it was a domestic abuse situation.
Rowena and Ariel's lawyer Kathryn Kraus said Jennifer and Gretl Petelczyc were Bombara's proxies for "the wife and child that he could not kill".
In the months before the fatal shootings, Ariel and Rowena were in contact with police on several occasions about Bombara and his access to guns, and their fears for their safety.
Superintendent Andrew Wilson said an investigation into the police who interacted with them found officers had not correctly assessed the risk Bombara posed.
Police powers that could have led to Bombara's guns being seized weren't used, said Supt Wilson, who lead an internal investigation into police conduct after the shootings.
Bombara also groomed junior police officers in April when they accompanied Rowena and Ariel to their family home, where Bombara was living, to collect their belongings.
The gunman was "overly helpful, jovial and manipulative" with the officers as he sought to manage the conversation about his guns for his benefit, Supt Wilson said.
He said the investigation found there was information at the time that could have enabled officers to issue a police order that would have allowed them to investigate Rowena and Ariel's firearms concerns.
Eight officers were disciplined following the investigation, he sald.
The inquest continues.
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