Police will investigate whether officers were lured to a remote Queensland property where two constables and a member of the public were killed in a shooting rampage on Monday.
Commissioner Katarina Carroll said investigators would also be looking at the online presence of the attackers, who were shot dead by police in a six-hour siege at Wieambilla, west of Brisbane.
A police source said graphic body camera footage would be used to piece together how Constables Matthew Arnold, 26, and Rachel McCrow, 29, and neighbour Alan Dare died.
The Queensland Coroner and the police service's Ethical Standards Command have launched investigations into the attack by Nathaniel and Gareth Train, and Gareth's partner Stacey Train.
Post-mortems were carried out on the bodies of the two slain officers on Wednesday, and the police union was set to discuss funeral arrangements with their families.
Forensic teams were back at the crime scene on Wednesday, doing a walk through as part of their investigations.
Commissioner Carroll told the ABC's 7.30 program police would "get to the bottom" of what happened, including whether the trio had planned the attack.
"We're definitely investigating every avenue, whether it be premeditated, some of the stuff that's online from these people. We will investigate what they have been doing not only in recent weeks, but in recent years, who have they been interacting with, family, friends, their online presence," Commissioner Carroll said.
The four officers had gone to the remote property to investigate a report about Nathaniel Train going missing from New South Wales in October when they came under fire.
NSW Police Commissioner Karen Webb said Nathaniel Train had been reported missing to Walgett police, in the state's north west, but she did not say by whom.
"Investigation around the circumstances of yesterday's horrible incident will be investigated, and is being led by Queensland police, so it would be inappropriate for me to comment about any avenues of inquiry," she said.
"Those officers were responding to a routine job. They were ambushed and they were executed."
Commissioner Carroll said the "specifics" of that tip-off from New South Wales Police would form a large part of the investigation.
"The initial call from New South Wales, the initial missing person's report, all of that will be investigated," she said.
The attackers appeared to be well-armed with a large calibre weapon and had a security camera system set up to alert them to anyone entering the property, the source said.
The two officers were shot without warning, as was a neighbour Alan Dare, who walked to the property's boundary after seeing cars on fire on the remote property.
Asked whether the attackers were wearing camouflage during the ambush, Commissioner Carroll said she "understood that may have been the case".
"I won't go into that aspect … I'm very mindful of what I can say as there will be a coroner's inquest," she said.
She said if the shooting was found to be premeditated, "it will be even more of a tragedy".
Commissioner Carroll said the four officers were "quite junior" but were comfortable with taking on what they believed to be a business as usual missing person job.
She said it was "not unusual" for four officers to respond to a missing person's report, particularly in rural areas where you go out with a neighbouring station.
"I know that the officer in charge also spoke to them, so they were quite comfortable going out to the property and in fact, from what I understand, quite jovial and having fun with each other. For us, this was a standard job," Commissioner Carroll said.
Asked what the preparation would have been for the officers before heading out to the job, she said a risk assessment had been carried out.
"We will always do a risk assessment, run those required checks to make sure that we have all the information that we need. And that was done on this occasion. They were comfortable going to this job as a BAU [business as usual] job," she said.
'She did not know if she would be shot or burned alive'
One of the officers managed to flee and raise the alarm despite being hunted by the attackers.
The officer, a policewoman, later identified as 28-year-old Constable Keely Brough, was highly praised by Queensland Police Union president Ian Leavers.
A second officer, Constable Randall Kirk, also 28, was shot in the leg and hip.
Mr Leavers said Constable Brough did not know whether she was going to be shot or burned alive.
"I do know she was sending messages to loved ones saying she was at a point where she thought it was her time. What was going through her mind, one cannot comprehend," he said.
Commissioner Carroll said Constable Kirk was expected to be released from hospital today.
"I met with Keely yesterday, Randall, I spoke to, he is still in hospital — we're hoping he’ll be released today and I’ll see him later this morning,” Commissioner Carroll said.
"They're doing as well as can be expected, they're grateful they're alive.
"It's a difficult time for them … because they were there when their partners were killed."
Commissioner Carroll said she would meet with the officers' families today.
She said the investigation into the shooting would "take days, if not weeks" and there would be a coronial inquest.
"We will go back, revisit every aspect of this … what we know about these people, how we responded, were they known to us?"
A vigil was held at the Calamvale Police Station in Brisbane's south last night.
Constable Arnold lived near the area and one of the senior sergeants at the station trained him and Constable McCrow.
