The murder of two police officers at a rural Australian property in 2022 was not a religious terror attack, Queensland’s state coroner has found – despite authorities previously declaring it the first such case in the nation’s history.

Constables Matthew Arnold and Rachel McCrow were on a routine visit to the property at Wieambilla in December 2022 when Nathaniel, Gareth and Stacey Train ambushed and killed them.

The attack triggered an hours-long siege which ended with police fatally shooting the trio.

Now, in findings released on Friday, authorities have declared that the ambush was not an act of terrorism, while acknowledging that the Trains were religious fanatics and conspiracy theorists.

State Coroner Terry Ryan said the trio acted “defensively within their delusional framework to defend themselves and their property from what they regarded was an evil advance on them”.

“In the months before 12 December 2022, they had been seeking to dissuade police engagement with them on their property, just as they took detailed steps to fortify their property against such engagement and waited to ambush any police who crossed their boundary,” Mr Ryan said.

“For these reasons, I accept the submission that it is not possible to conclude that Gareth, Stacey and Nathaniel committed a terrorist act.”

Mr Ryan further acknowledged that Australia’s legal definition of terrorism, as laid out in 2002 to respond to “large, well-planned and well-financed activities”, is “unhelpfully narrow and may not reflect the current security landscape”.

Arnold and McCrow – aged 26 and 29, respectively – were among four officers who visited the remote property, located about 270km (168 miles) west of the Queensland capital of Brisbane, on 12 December 2022.

They were there to check on a man who had been reported missing in the neighbouring state of New South Wales.

“For us, this was a standard job. We go to thousands of these every week,” Queensland Police Commissioner Katarina Carroll has said.

After arriving at the property, leaving their cars and approaching the house, however, the officers were inundated with gunfire from high-powered rifles and shotguns.

Arnold and McCrow were hit immediately. A third officer ran to find cover, while the fourth was able to retreat into his car, suffering a bullet wound to his leg on the way.

Police would later tell the Australian Broadcasting Corporation (ABC) that the “ruthless, murderous” Trains executed Arnold and McCrow while they were laying on the ground.

At some point a neighbour, 58-year-old Alan Dare, also turned up at the property, reportedly after spotting smoke. He was fatally shot in the back.

In his findings, Mr Ryan said it was “difficult to see how any responding officers could have been adequately equipped to respond to the events as they unfolded”.

Senior Sergeant Tracy Bailey of Queensland police, who was quoted in the findings, said “it would appear that the offenders were prepared for a lethal confrontation with any person that entered the property and there was nothing the officers could have done to prevent this.

“The offenders were waiting for them.”

Nathaniel Train was found to be Arnold’s killer, and his brother Gareth was found to have killed McCrow.

Nathaniel Train was a former school principal. He was also the missing man police were at the property to check on.

Gareth Train and his wife Stacey co-owned the property.

The coronial inquest found that Gareth Train had developed anti-government and conspiracy theorist views over the course of several years, and that his attraction to the latter appeared to have intensified after the 1996 Port Arthur massacre, where 35 people were killed by a lone gunman at a small town in Tasmania.

In 2012, Gareth Train complained that his phone had been tapped and said he was suspicious of police. By 2014, he spent significant periods of time researching conspiracy theories, Mr Ryan found.

These interests intensified in later years as Gareth Train became increasingly isolated, particularly during the Covid pandemic, and began communicating online with other fringe organisations and anti-government news forums.

In September 2020, he wrote in an online post: “Be warned QPS [Queensland Police Service] you all have a choice to make be on the right side, or face execution after”.

His comments and online rhetoric would later become increasingly religious, and his wife and his brother soon shifted in a similar direction – with both of them increasingly referencing what they saw as the approaching end times.

The inquest heard that the Trains’ conspiracy theories and beliefs caused significant conflict between them and their families.

It also heard that NSW police did not pass on emails, including several from Nathaniel Train’s wife, that might have alerted Queensland officers to the danger of engaging with the trio.

Mr Ryan said this was “regrettable”, noting that “the missed opportunities for further inquiries to have been made must be extremely distressing for the families of Constable Arnold, Constable McCrow and Mr Dare”.

Mr Ryan made 10 recommendations focused on improving police safety, including the provision of more drones for remote and rural police to help make risk assessments.

Australia introduced some of the world’s strictest gun regulations after the Port Arthur massacre.

Some of those regulations have since been watered down in various parts of Australia over the past 20 years, experts in gun control have warned – pointing out that some laws are not uniform across different states.