Brothers Nathaniel, 46, and Gareth Train, 47, used high-powered rifles during an ambush to kill Constables Matthew Arnold, 26, and Rachel McCrow, 29, at a remote property at Wieambilla west of Brisbane, on December 12, 2022.
Nathaniel Train joined Gareth and his sibling's wife Stacey, 45, to fatally shoot neighbour Alan Dare, 58, soon after killing the two constables.
All three Trains were shot dead by specialist police officers hours later after refusing to negotiate or surrender.
State Coroner Terry Ryan will hand down his findings in a Brisbane courtroom on Friday after considering evidence over the 14 months since a five-week inquest.
Mr Ryan previously heard evidence from consultant forensic psychiatrist Andrew Aboud that the Trains had a "shared psychotic delusion".
The trio believed police were Satan's demons coming to forcibly transform them into subhuman "meat puppets", Dr Aboud said.
The shootings were a "religiously motivated terrorist attack" motivated by a Christian extremist ideology, Queensland Police Assistant Commissioner Cheryl Scanlon said.
Constables Arnold and McCrow had attended the property with fellow Constables Randall Kirk and Keely Brough on behalf of NSW police.
Constables Kirk and Brough narrowly escaped being killed by the Trains.
Nathaniel Train had been reported missing from his state primary school principal job in northern NSW.
He was also subject to an arrest warrant in Queensland after abandoning some of his firearms while illegally crossing the border during COVID-19 lockdowns.
Speaking on the final day of the inquest, Const Arnold's mother Sue said her family and the McCrows still had critical unanswered questions.
