Police were repeatedly called to a Perth house before a mother and two of her children were fatally attacked there, Commissioner Chris Dawson has confirmed.
Teancum Vernon Petersen-Crofts, 19, was charged with three counts of murder on Monday after his mother Michelle, 48, and eight-year-old brother Rua were found dead inside their Ellenbrook home on Sunday.
His sister Bella was found critically injured in the backyard but died on the way to hospital.
"I can confirm that police have attended at that particular address, not only on the Friday, but in the weeks leading up to that," Mr Dawson told reporters in Perth on Tuesday.
"But these are matters that will be ultimately put before a court and, indeed, the state coroner, so I'm not going to particularise what exactly took place there."
Mr Dawson said he was confident the actions taken by officers who attended the home in the lead-up to the killings were appropriate in the circumstances.
Petersen-Crofts reportedly presented at a Midland hospital in a "psychotic state" on Saturday, but was turned away.
Deputy Premier Roger Cook declined to comment on any treatment he may have received.
"Obviously, we all want to get answers, and answers will be sought and we will get those answers," he said.
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