In the days and weeks leading up to a triple murder in which a New Zealand mother and her two children were killed in their Perth family home, police were repeatedly called to the address.

A WA Police spokeswoman declined to comment as to why police attended the house on Brixton Crescent in Ellenbrook prior to Kiwi Michelle Petersen, 48, her daughter Bella, 15, and son, Rua, 8, being killed there on Sunday.

"As this matter is now before the courts and the coroner, we are unable to make further comment," the spokeswoman told news.com.au.

Teancum Vernon Petersen-Crofts, 19, who is understood to be the son of Michelle and brother of the other victims, has been charged with their murders. Photo / Supplied
Teancum Vernon Petersen-Crofts, 19, who is understood to be the son of Michelle and brother of the other victims, has been charged with their murders. Photo / Supplied

Teancum Vernon Petersen-Crofts, 19, who is understood to be the son of Michelle and brother of the other victims, has been charged with their murders.

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Commissioner Chris Dawson today revealed police were called to the address on multiple occasions before Petersen and two of her children were fatally attacked.

"I can confirm that police have attended at that particular address, not only on the Friday, but in the weeks leading up to that," 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."

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.

Just hours before the frenzied attack, Peterson-Crofts reportedly presented to St John of God Midland public hospital, in a "psychotic state".

According to WA Today, Peterson-Crofts was turned away by the emergency department, on Saturday evening. A hospital spokeswoman declined to comment on the unverified reports — citing privacy reasons — when contacted by news.com.au.

Deputy Premier Roger Cook would not say whether or not Petersen-Crofts had been treated for any medical conditions prior to the tragedy.

"Obviously, we all want to get answers, and answers will be sought and we will get those answers," Cook said.

Assistant Commissioner Paul Steel earlier told reporters that a senior homicide squad investigating officer had said it was "potentially the most horrific crime scene he has ever been called to".

"It is a very complex and I would say horrific crime scene," Steel said.

Police were seen taking a pair of scissors from the home after the bodies were discovered.

L-R: The Petersens - Rua, 8, mother Michelle, 48, and Bella, 15 - were found dead in their Perth home. Photos / Supplied
L-R: The Petersens - Rua, 8, mother Michelle, 48, and Bella, 15 - were found dead in their Perth home. Photos / Supplied

Petersen-Crofts appeared before in the Midland Magistrates Court to face the three murder charges on Monday.

"A criminal wanted to take me out bush — he did it and he came back for my family," he told the court.

Magistrate Greg Smith responded by informing the accused he didn't need to say anything.

"I have to 'cos mamma is with me," Petersen-Croft continued.

"I was painting a picture of Jesus and stayed there for two months.

"He punched me in the head so hard. I left because I had to. I was that scared he was going to kill me.

"Mamma told me to save myself."

Petersen-Crofts then told a security guard he looked "like a serial killer". He was remanded to a psychiatric facility at Graylands Hospital and will face Stirling Gardens Magistrates Court next week.