Man Who Murdered 'Unsuspecting' Wife, Children And Mother-In-Law Jailed

A man who admitted using knives to murder his wife, three young children and mother-in-law has become the first person in Western Australia ordered by a judge never to be released from prison.

Anthony Robert Harvey, 25, 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.

Grandmother Beverley Ann Quinn, 73, was murdered when she visited the next morning, the WA Supreme Court heard on Friday.

Justice Stephen Hall said Harvey's crimes were so exceptionally horrific that he should never be free, making him the first person to face such an order under laws changed in 2008.

He said the women were unsuspecting, while the children were asleep when they were attached.

Police officers confronted by a brutal scene inside the family home. Source: AAP.

The murders were gruesome: the family had been killed with a combination of blunt force trauma and stabbing.

At the time Assistant Commissioner Paul Steel described the mass killing as a "tragic event" and described the discovery of the bodies as a traumatic event for the first responders, as well as for the family and wider community.