A murderous gunman's daughter says she repeatedly told police about her father's stash of weapons amid fears for her own life before he shot dead two people.
Registered firearms owner Mark James Bombara, 63, killed Jennifer Petelczyc, 59, and her daughter, 18-year-old Gretl, at their Perth home in an attack described as chilling and horrific.
He was searching for his estranged wife when he went to the house and fatally shot them and himself as police arrived at the property on Friday.
His daughter Ariel Bombara said she and her mother had fled the home they shared with him in late March "in fear of our lives and to remove ourselves from an abusive situation".
"I spoke with police on three separate occasions to raise the alarm about my father," she said in a statement on Tuesday.
"On each occasion, I alerted officers to my father’s guns and told them my mother and I felt there was a real and imminent threat to our lives."
Ms Bombara said she told officers one of her father's 13 guns, a Glock pistol, was missing.
"My understanding is this ultimately would be one of the weapons my father used to take the lives of two innocent women," she said.
Police rejected Ms Bombara's request for a 72-hour temporary protective order.
"We were told 'no' and that there was nothing police could do about the situation at that time,'' she said.
Officers escorted Ms Bombara and her mother to their former home on April 2 to collect belongings and she again warned police about her father's guns.
"One officer said 'Oh don’t worry, we know all about the guns' and when he called for backup he warned his fellow officers to wear bulletproof vests," she said.
Ms Bombara claims she and her mother were ignored by five different male police officers on three occasions when they tried to report their concerns.
"By that point, we felt completely helpless and I had to focus on getting mum to safety," she said.
"I did everything I could to protect my mother and when my father couldn’t find us he murdered her best friend and her best friend’s daughter."
Police Commissioner Col Blanch said an internal investigation had been launched into Ms Bombara's claims and would run alongside the coronial inquest, possibly with Corruption and Crime Commission oversight.
"Ariel's statement concerns me greatly," he said.
"The investigation will determine what we knew at the time and what decisions were made at the time and whether or not they were appropriate."
He confirmed Ms Bombara and her mother had contacted police three times between March 28 and April 2 and a family violence incident report had been recorded.
Premier Roger Cook empathised with Ms Bombara.
"She's been through an incredibly harrowing experience ... there must be a range of emotions that she's experiencing at the moment - anger would be one of them," he said.
Ms Bombara said police should have acted sooner to stop her father but they had failed.
"Those failures have cost the lives of two incredible women," she said.
"My mother and I made clear that lives were at risk ... I want answers."
The murders have shocked Western Australian and raised questions about whether the state's proposed tough new gun laws being debated in parliament go far enough.
