Anthony Robert Harvey, 24, was charged with the murder of his twin two-year-old girls, their sister, 3, their mother, 41, and their grandmother, 73, in the west coast city on September 3 and 4, Western Australian police commissioner Chris Dawson told reporters.
A 24-year-old man has been accused of killing his wife, three toddlers and mother-in-law with a blunt instrument and knives at their suburban family home, where he remained for several days before turning himself in, Australian police said Monday.
He allegedly killed Ms Quinn on the morning of September 4 when she arrived at the house.
It is understood Mr Harvey remained at the home "for several days" before heading to the police station in Karratha, although police are still working through a number of timelines.
"No matter that most of us did not know this immediate family, there's a sense of shock and at times even anger at what has taken place", Dawson said.
The family has not been formally identified, but Australian media named the mother as Mara Quinn, a fly-in fly-out worker - an employee who is flown in temporarily to a remote location for a period of time - for a West Australian mining firm.
WA Police Commissioner Chris Dawson said Harvey had spent "some days" in the Coode Street house before making his way to the Pilbara town.
A Facebook profile believed to be Mara Quinn's showed her cradling a newborn in her arms, with a man beside her, and stated that she was engaged in August 2014.
A real estate listing showed a modest three-bedroom house and a standalone garage.
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Taryn - who is the daughter of Beverley, sister of Mara and aunt to Charlotte, Alice and Beatrix - said the world was a "much sadder place without them".
"She was very much family-orientated, and she loved her daughters and grandchildren, and would have done anything for them".
"This world is a sadder place with the loss of these five attractive people but Heaven has gained five new angels", the family said.
"She was pretty unlucky in love before she met him", a friend told Fairfax Media.
"We could hear and see the kids playing in the backyard quite often".
Just over two months later, a 19-year-old man allegedly murdered his mother, sister and brother in Ellenbrook in Perth's northeast.
A grandfather shot his wife, daughter and her four children before taking his own life at a farm in Osmington, near Margaret River, in May.
Harvey was not required to enter a plea in court at this stage.