Police need to answer if they let down the terrified family of a gunman before he murdered two people, a federal minister says, as calls grow for an independent probe into the tragedy.
An internal police investigation will look at the handling of interactions with the daughter and ex-wife of Mark Bombara, who had fled "out of fear of their lives".
But the WA opposition and a WA senator are also calling for an independent probe into the events leading up to the deaths.
Bombara killed Jenny Petelczyc, the friend of his ex-wife, and her 18-year-old daughter Gretl Petelczyc in their Floreat home, before taking his own life.
His daughter, Ariel Bombara, claimed WA police ignored repeated warnings her father was dangerous and had several guns.
Bombara believed his ex-wife had been staying at the Floreat house.
Ms Bombara said their pleas for help "were repeatedly ignored" and they had been "repeatedly failed" by police.
Federal Social Services Minister Amanda Rishworth said an investigation into what went wrong was an appropriate measure.
"It certainly seems that she (Ms Bombara) did not get the response that she needed from police," she told ABC News Breakfast on Wednesday.
"So it's right that the Western Australian government looks into this and it's right that the police commissioner looks at what could have been done in this circumstance to prevent this tragedy."
WA Police Commissioner Col Blanch rejected the force didn't act after it was approached by the women.
"To say nothing was done is wrong. A lot was done," he told ABC radio.
Greens Senator Dorinda Cox, a former police officer from WA, said independent oversight of the investigation into the murders was needed because she didn't trust police.
"Police investigating police is not the best practice solution," she told ABC's RN.
It was in everyone's best interests to have that conversation in quite a public space, she said.
"It's not about blame, and it's not about criticism, it is about actually getting to improvement in the system, improvement in our responses, and saving the lives of women and children in this country."
Senator Cox said the nation was at a "crisis point" with a disproportionate amount of women dying across the country.
WA Police Minister Paul Papalia said police did not receive a formal record of complaint from Ms Bombara and her mother about violence in the weeks leading up to the shooting.
"I understand that, the police were approached by Ariel and her mother, and what they reported did not meet the threshold for application of a police order," he said.
"The premier has asked the police commissioner and me to look at that.
"My personal view is there is a need to lower the threshold."
WA Opposition leader Shane Love and WA Liberals leader Libby Mettam called for a parallel independent investigation led by the Crime and Corruption Commission.
Mr Love said Mr Papalia oweed the Bombara and Petelczyc families an explanation about why police failed to act on the warnings.
"He also owes them an apology for trying to spin their tragedy into political point-scoring," he said.
Mr Love said Mr Blanch must inform the public when the internal investigation would be completed and if it will be made public.
Ms Rishworth praised Ms Bombara's decision to speak out and said her statement had been "incredibly powerful".
"It requires an enormous bravery, particularly at a time when she would be grieving, to speak up and make these comments," she said.
"Her urge for action is also very powerful."
Deputy Liberal leader Sussan Ley said all options needed to be on the table to make sure an incident like that in Perth doesn't happen again.
"Women everywhere feel like they have been failed and they have, we have failed women everywhere," she told reporters in Canberra.
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