Investigators are still probing the shooting deaths of Constables Matthew Arnold, 26 and Rachel McCrow, 29, and 58-year-old Alan Dare, at a rural property at Wieambilla, three hours west of Brisbane, on December 12.
They're yet to declare a motive but are investigating the link between shooters Nathaniel Train, his brother Gareth and sister-in-law Stacey, who were all shot dead by specialist police, and online conspiracy groups.
The trio's activities in the physical world, such as stockpiling weapons, setting up surveillance systems at the property and alleged illegal border crossings, are also being probed.
Nathaniel Train allegedly breached COVID-19 rules by sneaking from NSW into Queensland and dumping guns, ammunition, hunting gear and paperwork into a creek in December 2021, the ABC has reported.
Queensland Police Minister Mark Ryan has refused to say if he was briefed about that particular incident, which occurred almost exactly one year before the Wieambilla killings.
"I don't want to comment on the accuracy or otherwise of your statement," he told reporters on Tuesday.
"It is a full investigation that matters are before the coroner. The (police) commissioner has been very clear that there will be a very thorough investigation and the coroner will look at all aspects of this matter."
Investigators are probing the circumstances of the attack, which fellow constables Keely Brough and her colleague Randall Kirk managed to escape.
When asked why four police had been sent to check on Nathaniel Train, who had been reported missing by family in NSW, Mr Ryan said that it was common practice in regional areas.
Meanwhile, the minister said he had already spoken to the police union about their "very good idea" for the Trains' property to be bought and converted into a memorial, retreat or police training centre.
"I'm very supportive of that, in my view, that ground is now sacred ground, that is where the lives of two heroes of Queensland were taken, and I can think of no better way than to preserve that forever," Mr Ryan said.
Queensland Police Union president Ian Leavers on Tuesday called for the government to help the union buy the remote bushland block to ensure it never fell into the hands of "conspiracy theorists".
"The QPU would never want to see this land fall into the hands of any other anti-vaxxer, pro-gun conspiracy theorist, sovereign citizens who may seek to utilise the reputation of this site to promote their own dangerous and warped views," Mr Leavers said in a statement.
"This site is one that we as police have a duty to protect, and we will ensure its future usage is both appropriate and sympathetic."
Some 8000 people are expected to attend a public memorial at the Brisbane Entertainment Centre on Wednesday before family and friends farewell the constables at private ceremonies.
Members of the public are invited to attend the ceremony alongside family, friends, dignitaries and police officers. Free tickets were available from Monday night.
The service will be live-streamed online and on TV, and Queenslanders will be able to watch the event at a number of public venues around the state, including in communities near Wieambilla such as Tara, Dalby and Chinchilla.
