The family who fatally shot two police officers and a neighbour thought they would "die fighting for God" in an incident fitting the definition of terrorism, a coroner has heard.
State Coroner Terry Ryan on Tuesday heard from Deakin University politics professor Josh Roose about the political, religious and ideological influences behind the shooting that claimed six lives in rural Queensland.
Nathaniel Train, 47, his brother Gareth, 46, and his sibling's wife Stacey, 45, fatally shot police constables Matthew Arnold, 26, and Rachel McCrow, 29, without warning at Wieambilla, west of Brisbane on December 12, 2022.
Gareth Train was an angry man who felt disempowered, Professor Roose testified.
"He saw the world as corrupt, people behind the scenes were pulling the strings and he had a role to combat that," he said.
Mr Ryan heard Gareth Train communicated with fringe political parties and movements such as the sovereign citizens, who refuse to recognise laws, but left after finding them boring.
Prof Roose said Gareth Train posted on an online forum "Queensland Police have the opportunity to be on the right side or face execution".
The coroner previously heard from a forensic psychiatrist the Trains suffered from a "shared psychotic disorder" with Gareth Train the primary sufferer.
Prof Roose said he accepted that opinion but found they had engaged in "the definition of a terrorist act" after Gareth Train embraced conspiracy theories and an extremist Christian premillennialism belief the world would end in early 2023.
"Stacey had created a detailed timeline in her notebooks. She spent hours and hours trying to determine when this would occur," Prof Roose said.
He said the Trains did not lure police to their property but had taken shifts in hidden sniper positions in preparation for "ideologically motivated terrorism" in the form of a battle with "devils and demons" amid the second coming of Jesus Christ to secure the family's salvation.
"They were online that morning ... trying to recruit a woman to come to Australia," Prof Roose said.
The shooting started when four junior officers arrived at the bush block property west of Brisbane to serve an arrest warrant on Nathaniel Train.
The brothers fatally shot their neighbour Alan Dare, 58, before the police Special Emergency Response Team (SERT) killed the Trains later that night.
SERT commander Superintendent Tim Partridge returned to give evidence and said he would have benefited from having a sniper positioned in a helicopter above the Trains' property.
"We were significantly hindered ... the officers in the armoured vehicles were unable to get a clear shot in order to engage (the Trains) because they were cowering behind logs and in defensive positions," he said.
Supt Partridge said "helicopter fire support" might have been the only option to quickly stop the Trains if they had attempted to flee in a vehicle.
Mr Ryan heard Queensland was the only state that did not deploy police snipers in helicopters or was obtaining that capability.
Christian Gericke testified on Tuesday as to whether Nathaniel Train suffered brain damage and if this had affected his behaviour or caused psychosis.
Mr Ryan previously heard Nathaniel Train suffered a heart attack and had to be resuscitated 16 months before the shootings.
Following his heart attack, Nathaniel Train abandoned his successful teaching career and illegally crossed the NSW-Queensland border during COVID-19 lockdowns with a cache of firearms.
Professor Gericke said he had reviewed Nathaniel Train's medical records and found "positive evidence" to disprove he did not have an enduring brain injury from lack of oxygen following his cardiac arrest.
"There is very good evidence (Train) did not suffer from this," he said.
Prof Gericke said "large parts" of Nathaniel Train's brain were available to test at his autopsy, which offered the most accurate results for physical signs of hypoxic ischemic encephalopathy.
"There was no damage ... except for the bullet. That caused some damage," he said.
