Mass killings are rare in Australia, but this appears to be the third such family tragedy to hit Western Australia state in recent months.
The bodies of his wife, Mara Lee Harvey, 41, her 3-year-old daughter Charlotte, 2-year-old twin sisters Alice and Beatrix, and their grandmother Beverley Quinn, 73, were found at the home in the suburb of Bedford on Sunday after Anthony Harvey alerted police in Karratha.
"That will take a period of time and it could be a number of days", Assistant Police Commissioner Paul Steel said.
The women were allegedly attacked in the kitchen, while the children were killed elsewhere in the house.
He is believed to have remained at the house for "some days" before heading north.
In a heart-warming tribute issued via police, the sister of the family of the five people killed in WA has described Mara Harvey as a loving mum and thanked the public for their wishes during a "dark and hard time".
A real estate listing showed a modest three-bedroom house and a standalone garage.
"This world is a sadder place with the loss of these five handsome people but heaven has gained five new angels", she said in a statement.
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"We noticed that the house next door was pretty quiet, which was unusual", said Richard Fairbrother, who lives next door to the family's house.
"We had some friends staying here who have also mentioned that they didn't see or hear anybody next door for the week that we were away. we could hear and see the kids playing in the backyard quite often".
"Our heart goes out to the family and friends of all involved and also to the first responders who had to witness that disgusting situation", Cook said.
A bouquet of red roses with a card saying "rest in peace, neighbours" was placed near the house.
In July a man allegedly killed his mother and two siblings.
A man was charged with murdering his three daughters, his wife and her mother in Australia, police said.
Harvey is expected to return to court on September 19.