Stou Daniels, Davy Malu Junior Taiao and Trent Michael Thrupp are charged with murdering Cory Breton, 28, and Iuliana Triscaru, 31, at Kingston in Logan, south of Brisbane, on January 24, 2016.
Ngatokoona Mareiti on Thursday told a Queensland Supreme Court jury she went to a Kingston residential unit to buy drugs, arriving a few hours before the alleged murders, and saw Mr Breton and Ms Triscaru on a couch.
The jury heard Daniels asked Mareiti to go out to buy Jack Daniel's whiskey and she went to two shops to find that brand.
"We drank the alcohol … they had a PlayStation there," she said.
Mareiti said when she returned to the unit she could hear Ms Triscaru calling out from inside the toolbox and she assumed Mr Breton was in there too.
"I couldn't see him in the unit," she said.
The jury heard Mareiti had previously pleaded guilty to manslaughter over the pair's deaths.
Crown prosecutor Nathan Crane previously told the jury he would allege Daniels and Taiao were liable for murder by forcing the alleged victims into the toolbox at the unit at Kingston in the hours before their death.
Thrupp either threw the toolbox into nearby Scrubby Creek or was present when it happened, Mr Crane said.
Police divers found the pair's remains in the toolbox two weeks later.
Earlier on Thursday, Lelan Harrington testified he was not present when the toolbox was thrown into the water.
Defence barrister for Thrupp, Jessica Goldie, asked Mr Harrington if he was lying when he said her client told him he killed the alleged victims.
"I suggest to you at no stage has Mr Thrupp ever made comments to you about shooting Mr Breton and Ms Triscaru and you just completely made that up," Ms Goldie said.
"No, that's exactly what he said," Mr Harrington said.
Ms Goldie asked Mr Harrington about his previous statement that, hypothetically, he would have shot the pair in the head.
"That is the truth, isn't it? You are responsible for what happened to Mr Breton and Ms Triscaru?" Ms Goldie said.
"No," Mr Harrington said.
Mr Harrington accepted he was given a suspended sentence for detaining and assaulting Mr Breton and Ms Triscaru after agreeing to give evidence for the prosecution.
He admitted lying to investigators in February 2016 to conceal the defendants' alleged suspicion the alleged victims were informing police about their drug dealing.
"Yes, I did lie for them so they did not go to jail," Mr Harrington said.
All three defendants pleaded not guilty to two murder charges at the start of their trial on Monday.
During his second day giving evidence, Mr Harrington, a flatmate to some of the defendants, continued being cross-examined by defence barristers.
He admitted he initially lied to police in an effort to protect his friend, named as a chief offender by Mr Crane, from being charged with murder.
"I said 'f*** it' and then told the truth," Mr Harrington said.
He denied holding a grudge against Mr Breton over claims he assaulted someone close to him when they could not pay for drugs.
Mr Harrington told the jury he was sure about his testimony about Taiao assaulting Ms Triscaru.
"You saw a cable tie placed around her neck by my client?" barrister Lars Falcongreen said.
"I have got a clear picture of that," Mr Harrington said.
The trial before Justice Glenn Martin is due to continue for another two weeks.
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