Constables Matthew Arnold, 26, and Rachel McCrow, 29, had jumped a fence at a property at Wieambilla, west of Brisbane when Nathaniel, Gareth and Stacey Train opened fire and killed them.
Neighbour Alan Dare was also shot dead before the Trains were killed in a gunfight with specialist police on the night of December 12.
A year on from their heinous killings, emotions are still raw as the Arnold and McCrow families approach a second Christmas without their loved ones.
Constable McCrow's sister recently gave birth to a boy - a nephew she will never meet.
Constable Arnold was a triplet and his family was still grappling with his death, Queensland Police Union President Ian Leavers said on Tuesday.
"That gut-wrenching pain, which all of us felt on that day, will never, ever be forgotten," Mr Leavers said.
"The way that they were callously executed in cold blood has resonated with every police officer in Queensland because they know it didn't have to occur, it should never have occurred, but it could have been any one of them, just responding to a call for service."
A year on from the killings, the police union is adamant it will one day acquire the Wieambilla property so it can never again "be used for evil".
As well as the minute's silence, Commissioner Katarina Carroll and dignitaries will attend a wreath-laying ceremony at Brisbane's Queensland Police Service Memorial to mark the 4.36pm anniversary.
Police radios will fall silent for a minute to mark one year since the fatal shootings. (Darren England/AAP PHOTOS)
"Matthew and Rachel's family ... are in pain each and every day, and they do not want to publicly come out on the anniversary," Mr Leavers said.
"But they've asked me to convey the message - please never forget Matthew, never forget Rachel, don't forget their families, but make sure that (we do) anything that we can do (to) prevent a tragedy like this happening into the future.
"Don't let their deaths go in vain."
The Arnold family released a statement saying December 12 marked a day of "incomprehensible evil".
"We miss Matt's laugh, kindness, empathy and willingness to help," they said in a statement released by Queensland Police.
"These traits were what made him such an excellent police officer and made him love his job."
The family also paid tribute to the bravery and courage of Const McCrow.
"We will forever stand with the McCrow family in the pain they feel with losing Rachel," they said.
"We also remember Alan Dare on this day."
Following years of concerns about gun-related crime around Australia, a meeting of federal, state and territory leaders last week agreed to establish a National Firearms Register within four years.
The agreement was reached on the day a US man was arrested by the FBI in connection with the Queensland attack.
Conspiracy theorist Donald Day Jr is accused of sending "Christian end of days ideology" to the Trains in the lead-up to the killings after they connected on YouTube.
Stacey and Nathaniel Train's children Madelyn and Aidan on Tuesday distanced themselves from their late parents' "religiously extreme beliefs", saying they would mark the first anniversary by grieving the victims.
"All who are hurt by the loss of Rachel, Matthew and Alan have our condolences and sympathy," they said in a statement.
"We are truly sorry for the suffering our parents have caused and the impact their actions continue to have."
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