The pair had been beaten, stabbed and choked before they were stuffed into the two metre-long container.
They were likely "screaming for their lives" when the toolbox was later dumped in a lagoon south of Brisbane in January 2016.
Almost 10 years later, Stou Daniels, Davy Malu Junior Taiao and Trent Michael Thrupp were found guilty of the pair's murder for a second time.
They faced a retrial in Brisbane after the Court of Appeal set aside murder convictions in July 2024.
Mr Breton, 28, and Ms Triscaru, 31, had been lured to a residential unit at Kingston, south of Brisbane, before being attacked by a group of men.
"It was torturous. They were assaulted when they arrived and throughout the day ... while bound with cable ties and duct tape," Crown prosecutor Nathan Crane told the weeks-long trial that concluded with Friday's verdicts.
They were attacked, interrogated and threatened over a drug dealing dispute.
When Ngatokoona Mareiti arrived at the unit to buy drugs, Mr Breton and Ms Triscaru were sitting bound on the couch.
Sent away to buy whiskey, by the time Mareiti returned she could not see the pair and assumed they were in the toolbox at the unit.
They drank and played video games as the bound pair were held captive in the container nearby.
"We drank the alcohol … they had a PlayStation there," Mareiti told the jury.
Cloths and bleach used to clean bloodstains in the unit were thrown into the toolbox before it was taken away with Mr Breton and Ms Triscaru still inside.
The terrified pair made so much noise as the container was being moved, music from an awaiting ute was turned up in a bid to conceal it.
"The transition of the toolbox to a HiLux utility vehicle attracted attention from those present at the unit complex - there was noise emanating from the toolbox," Mr Crane said.
"There was music used from the HiLux to cover up the sound."
Thrupp either threw the toolbox weighed down by concrete into nearby Scrubby Creek or was present when it happened, Mr Crane said.
Daniels and Taiao were also liable for murder by forcing the victims into the toolbox hours before their deaths, he said.
Police divers found the bodies locked in the toolbox submerged in the creek two weeks later.
"Most likely the two ... were alive and screaming for their lives when they were placed in the creek," Justice Peter Davis said in 2020 when sentencing Tuhirangi-Thomas Tahiata, who drove the ute to the creek.
"It is haunting to imagine the moment that the toolbox slipped under the water, plunging the night into silence."
Daniels, Taiao and Thrupp each pleaded not guilty to two counts of murder at their retrial.
The jury on Friday returned its verdict after deliberating since 10.45am Wednesday.
The trio will be sentenced on Thursday.
Overall seven men and a woman were charged over what became known as the "toolbox murders".
Tahiata received a life sentence for murder, unsuccessfully appealing the conviction in April 2024.
Mareiti, Webbstar Latu, Tepuna Tupuna Mariri and Waylon Ngaketo Cowan Walker were found guilty of manslaughter.
However, Walker had his convictions overturned in July 2024.
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