The junior police officers on a routine job were unaware they were being watched by two heavily-armed brothers who believed authority figures to be demons.
Queensland state coroner Terry Ryan on Thursday completed five weeks of hearings into the deaths of six people at a rural property on December 12, 2022.
Mr Ryan heard evidence of the many years and multiple unfortunate decisions, large and small, that led to a tragedy described by deputy police commissioner Cheryl Scanlon as "rare and devastating".
Constables Matthew Arnold, 26, and Rachel McCrow, 29, were shot dead at Wieambilla, west of Brisbane, as they walked up a driveway as part of a missing persons investigation.
NSW Police officers had asked their Queensland counterparts to attend the 40-acre bushland block in an effort to find Nathaniel Train.
Train had been a successful primary school principal in regional NSW before a heart attack threw the highly athletic and hardworking 46-year-old into a downward spiral.
He had been camping in remote Queensland for nearly 12 months while in sporadic phone contact.
Mr Ryan heard Nathaniel Train returned to his previous unconventional circumstances of living in isolation with his ex-wife Stacey Train, 45, who was now married to his 47-year-old brother Gareth Train.
Counsel assisting Ruth O'Gorman told Mr Ryan he should find the Trains suffered from a "shared psychotic disorder" with Gareth Train as the primary sufferer.
"The Trains were motivated by religious conviction that the end times were imminent … their religious extremism was a key driver for their actions," she said.
Ms O'Gorman said the Train's Christian premillennialist belief in an impending apocalypse and final battle with Satan was predated by their shared delusion they were being persecuted by a range of authorities, and particularly by police.
As the four officers at 4:37pm walked towards the house at the centre of the block, Nathaniel Train was less than 200 metres away in an improvised bunker.
Older colleagues referred to Wieambilla as 'The Blocks' and warned some residents had signs with threats to kill intruders and a perimeter of dangerous booby traps.
Nathaniel Train sat behind bullet-resistant hardwood logs that were camouflaged to look like the scrub that surrounded Gareth and Stacey Train's farmhouse.
Through the scope of his high-powered rifle, Nathaniel Train counted the number of officers and noted their positions before firing a single, fatal shot into Const Arnold's chest.
Gareth Train joined in firing on the officers with his own rifle, wounding Const McCrow while causing her colleagues Const Randall Kirk and Keely Brough to run for cover.
Ms O'Gorman said Const McCrow showed "great courage under fire" by continuing to record information about her attackers and shooting back with all 15 rounds from her pistol.
Gareth Train approached Const McCrow while she was lying on the ground and, after a brief conversation, fatally shot her in the head.
Nathaniel Train joined Gareth and Stacey soon afterwards and shot dead their neighbour Alan Dare, 58, who had come to investigate.
By 10:41pm that night, all three Trains had been killed by Special Emergency Response (SERT) police officers after refusing to negotiate or surrender.
The incident lasted six hours from first to last shot but evidence at the inquest suggested the deadly ambush was preceded by a long history.
NSW Police did not share all the information they had about the Trains with Queensland, including threatening emails from Gareth, but Ms O'Gorman said this did not spell out a potential risk to police.
Even if the junior officers who arrived at Wieambilla had assault rifles and the latest body armour, they would not have been likely to avoid fatal gunshots or effectively return fire at the concealed shooters.
A person close to Nathaniel Train travelled to Brisbane prior to reporting him missing, intending to ask a family member whether Gareth Train was dangerous, but found it unsuitable to raise the subject.
A triple-zero operator was unable to explicitly warn Alan Dare not to approach the Trains' property as she incorrectly feared punishment for "snooping" if she looked at details of a police-in-danger incident nearby.
Consultant forensic psychiatrist Andrew Aboud testified that his posthumous analysis of Gareth Train revealed a long history of concerning behaviour, including as a teenager asking two girlfriends to enter a suicide pact with him.
Dr Aboud said Gareth Train also likely had a paranoid personality disorder that manifested in long-held conspiratorial beliefs such as the Port Arthur massacre being staged to support gun control.
"It started taking over this life to the point he became fully delusional," Dr Aboud said.
The extent of the Trains' shared delusions were illustrated by an incident in 1999 when all three attended a wedding but were asked to leave after accusing guests of committing heinous and bizarre abuse as part of church rituals.
"This had a seismic effect … it created isolation from the rest of the family and from people who might have sought to challenge their thoughts," Dr Aboud said.
Soon after Nathaniel Train collapsed at work in 2021 with a cardiac arrest, Gareth told him not to let the hospital "put a monkey heart" in his chest.
Nathaniel Train later refused to take cardiac medication or receive a pacemaker-style implant.
This medical refusal led NSW Police to label Nathaniel Train's status as "high risk" and seek assistance from Queensland within a week of him being reported missing.
Dr Aboud said the Trains kept shooting at SERT officers because they feared a "fate worse than death" via delusions that police were demonic "meat suits" who would turn them into mindless slaves if arrested.
The families of Const McCrow and Const Arnold acknowledged the inquest's diligent work but say they still have critical unanswered questions about the "preventable" deaths of their loved ones.
Mr Ryan will receive written submissions over the next three months before making his findings.
"There are clearly lessons to be learned from this tragedy," Mr Ryan said in closing the hearings.
