Received

Investigators will track every keystroke of the Train family's dark path toward the deadly Queensland ambush that left six people dead, including two heroic police officers.

Constables Matthew Arnold, 26, and Rachel McCrow, 29, along with 58-year-old resident Alan Dare, were killed in a hail of bullets at a rural property at Wieambulla in the western Darling Downs region on Monday.

Prime Minister Anthony Albanese, who previously said the officers paid a price no one who puts on the uniform should ever pay, will lead tributes to the pair in federal parliament on Thursday.

Constables Randall Kirk and Keeley Brough, both 28, narrowly escaped the attack but the former was injured in the intense gunfire.

Their killers - former school principal Nathaniel Train, his brother Gareth and sister-in-law Stacey - died in a firefight with heavily armed tactical officers after an ambush on the four officers.

The Train brothers' father Ronald Train said he was struggling to comprehend how his sons could be responsible for the murderous attack.

"I just could not understand how something like this could have occurred, with two children who had been raised by my late wife Gwen and myself," the retired pastor told Nine's A Current Affair on Wednesday.

"They went down this track, this dark track, which we have no understanding of."

Police trying to identify the motive for the lethal attack will trace the brothers' online activities, delving into extremist communities online.

"We'll investigate their families, their friends, everything they've done in the last six months to a year," Queensland Police Commissioner Katarina Carroll said.

"We will get to the bottom of this because we need to know what happened and why."

Online posts in the name of Gareth Train featured a myriad of conspiracy material, including claims that high-profile shootings were hoaxes or false-flag operations.

Ronald Train revealed he officiated at the wedding of his younger son Nathaniel and Stacey some years ago, adding he was surprised when he saw reports the older Gareth was now married to the same woman.

The brothers cut all ties with their parents about 23 years ago, he said.

Alan Dare's widow Kerry spoke of her loss, describing her husband as a beautiful man who loved his children and grandchildren.

She was due to celebrate her 26th wedding anniversary on Wednesday but instead she was coming to terms with a life without Alan.

"I haven't thought about it yet ... I've got to be brave," she told A Current Affair through tears.

She said her husband was going to make sure his neighbour was safe after hearing multiple gunshots and seeing black smoke in the area.

Instead, Mr Dare was shot and left for dead.

"If he laid there, he wouldn't have been scared," she said.

"He would have been just looking at the sky and he would have probably been enjoying the view."

© AAP 2022

Queensland victims of crime are waiting to find out if their cases will be reviewed after a damning report into the government-run forensic lab.

A four-month inquiry into the state's embattled DNA testing system found it failed to properly test DNA samples for years because of "grave maladministration involving dishonesty".

The report revealed lab managers had focused on speed rather than accuracy in DNA testing, and "that scourge has invaded" the validation of process and equipment used, time management and resources.

Former judge Walter Sofronoff recommended Forensic and Scientific Services be restructured with an independent head scientist focused on scientific integrity and serving the criminal justice system.

Potentially "thousands of cases" could be reviewed, and crime scene samples retested for DNA, potentially by a panel including a scientist, a police officer, a prosecutor and a lawyer.

The Queensland government is expected to respond to the findings on Thursday.

© AAP 2022

A pair of junior Queensland police officers who survived a shooting ambush that claimed the lives of two fellow constables are grateful to be alive as investigators probe motives for the attack.

Constables Matthew Arnold, 26, and Rachel McCrow, 29, along with 58-year-old resident Alan Dare, were killed in a hail of bullets at a rural property at Wieambulla in the western Darling Downs region on Monday.

Constables Randall Kirk and Keeley Brough, both 28, escaped but the former was injured in the intense gunfire.

Const Kirk, who is expecting his second child with wife Bree next month, was due to be released from hospital on Wednesday after recovering from surgery to remove shrapnel.

The couple said they were overwhelmed by the messages of support from the public and "everyone from the prime minister down".

"I'm feeling fine, just a little sore. My main thoughts are with the other police families at this awful time," Const Kirk said in a statement released by the police union.

"It means a lot to know the community cares for us all."

Premier Annastacia Palaszczuk on Wednesday laid flowers at the Botanic Gardens Police Memorial in Brisbane to honour those killed in the attack.

"The constables were so young and brave, and Alan Dare, an innocent bystander," Ms Palaszczuk tweeted.

"We want the Queensland Police family to know that we respect and appreciate what they do for us. If you see an officer, please offer them a kind word as they grieve the loss of their colleagues."

Queensland Police Commissioner Katarina Carroll said constables Kirk and Brough were doing as well as could be expected and they were grateful to be alive.

"For them, it's very difficult ... they were there when their partners were killed," Ms Carroll told ABC TV.

Their killers - former school principal Nathaniel Train, his brother Gareth and sister-in-law Stacey - died in a firefight with heavily armed tactical officers after the attack on the four officers.

Hundreds of rounds were exchanged before the trio were shot and killed.

All three members of the Train family were considered active shooters and died with their weapons clutched in their hands, a police source told AAP.

One shooter was killed as he fired directly at the bulletproof windscreen of an armoured police vehicle as it approached the homestead.

Investigators are probing the motive for Monday's attack, including whether the officers were lured to the property after following up on a NSW missing person report for Nathaniel Train.

They will also examine how the brothers were able to stockpile a cache of lethal weapons, including high-powered firearms, knives and axes.

The weapons had been legally obtained but were registered in NSW, a source said, prompting calls for changes to national gun registration.

Queensland Police Union head Ian Leavers called for weapon licensing protocols to be reviewed, including how the national database functioned when people crossed state lines.

Reports the perpetrators were dressed in camouflage and whether the attack was premeditated will form part of the police investigation.

Investigators will also explore the killers' motivations and possible extremist links after a series of posts under the name of Gareth Train were uncovered on conspiracy theory forums.

The posts include references to anti-vaccine sentiments and claims high-profile shootings were hoaxes or false flag operations.

The brothers' father Ronald said Gareth had always been a volatile and overpowering person who was obsessed with weapons and guns.

The Train brothers cut ties with their parents 23 years ago but the retired pastor said he was still shocked the pair went down this violent path.

"They've been demonised by what's occurred and I can completely understand that," Mr Train told A Current Affair on Wednesday night.

"(They were) two boys who completely lost their way in life."

© AAP 2022