A Perth man who admitted being obsessed with serial killers before he murdered his three children, wife and mother-in-law has spent his first night behind bars knowing he will never be free again.
Anthony Robert Harvey, 25, pleaded guilty to murdering his family and has become the first person in Western Australia ordered by a judge never to be eligible for parole.
Harvey killed two-year-old twins Alice and Beatrix, three-year-old Charlotte and their mother Mara Lee Harvey, 41, at their Bedford home on September 3, 2018.
He killed grandmother Beverley Ann Quinn, 73, when she visited the next morning.
"There is no other case that is truly comparable," Justice Stephen Hall told Harvey in the WA Supreme Court on Friday.
"Your actions were so far beyond the bounds of acceptable human conduct that they would instil horror and revulsion into even the most hardened of people."
Justice Hall said Harvey carried out the crimes with "apparently calm deliberation" and failed in his duty as a parent "in the most extreme way imaginable".
In Harvey's journal he wrote about embracing his "darkness and animal instincts" and "doing the unthinkable to unshackle" himself from his family.
Ms Quinn and Ms Harvey were struck on the head with a 1.2 metre pipe and repeatedly stabbed with a newly-purchased large knife almost the size of a machete.
The children were murdered with a smaller knife and Justice Hall said there were more wounds than would appear necessary to kill.
Harvey remained at the house for days then gathered cash and travelled about 1500km north to Pannawonica where he turned himself in to police on September 9 with the help of his father.
Outside court, Ms Harvey's sister Taryn Tottman said the sentencing was "extremely suitable" but the family was also suffering a life sentence.
"Please remember my mum Beverley as a generous, committed, loving mum and friend that she was," she said.
"My sister Mara for her love, support and determination. My nieces Charlotte, for her enthusiasm and laughter, Alice, for her sense of adventure and cheekiness, and Beatrix, for her spirit and of course her hugs."
Australian Associated Press