Osmington shooting

On 11 May 2018, seven members of one family were found dead at a hobby farm in Osmington, Western Australia, in what was described as the worst mass shooting in Australia since the 1996 Port Arthur massacre until the 2025 Bondi Beach shooting. Peter Miles, a 61-year-old retired high school farm manager, had worked at the farm school at Margaret River Senior High School for twenty years. In 2015, he and his wife Cynda moved from the Margaret River townsite to a 12-hectare (30-acre) property in Osmington. His daughter, Katrina Cockman, and her four children — Tay (13), Rylan (12), Arye (10), and Kayden (8) — moved onto the property following the breakdown of Katrina's marriage, living in a renovated shed on site. Katrina believed the children were on the autism spectrum, and they had been withdrawn from local school for home-schooling.

Aaron Cockman, Katrina's estranged husband and the children's father, later said the Miles family had a history of violence, mental illness, and dysfunctional relationships, and that he and Peter and Cynda had been in conflict over legal fees and access to the children in the period before the shootings.

Police responded to a 000 call at 5:15 am on 11 May 2018. Peter Miles was found deceased in a chair on the veranda outside the property; his wife Cynda (58) was found inside the main house; and Katrina Cockman (35) and her four children were found inside the converted shed where they lived. Western Australia Police Commissioner Chris Dawson confirmed three rifles, all licensed to Peter Miles, were recovered at the property, and stated police did not believe anyone outside the residence was involved.

Aaron Cockman, in a press conference held forty-eight hours after learning of the deaths, said police had told him Peter Miles first shot Katrina and her four children while they slept, then shot Cynda in the living room, before placing a two-minute call to police and subsequently taking his own life. On 17 May 2018, Commissioner Dawson confirmed forensic work at the property was complete and access had been returned to the family, though the investigation would continue for several months. A suicide note was found, and Peter Miles was confirmed to have been taking SSRI-class antidepressants at the time.

In the aftermath, Aaron Cockman criticised the Office of the State Coroner for secrecy and unwillingness to share information with him. State Coroner Ros Fogliani declined his request for a public inquest, stating it was "not desirable" and that all relevant lines of inquiry had been followed. Cockman subsequently wrote to state attorney-general John Quigley reiterating his request. He has also expressed the belief that the Family Court of Western Australia placed the family under significant financial and emotional pressure prior to the killings, and has voiced support for a royal commission into Australian family law.