One of the eight people charged over the Logan toolbox double murder allegedly confessed to police but they didn't record it.
Tuhirangi-Thomas Tahiata is facing a committal hearing in Brisbane Magistrates Court after being charged with the murders of Cory Breton and Iuliana Triscaru in February 2016.
Prosecutors allege the pair were beaten at a Kingston unit in a dispute over a drug debt before being bound and stuffed in the two-metre long box.
They were then allegedly driven to the dam off a dead-end street where they were shot in the head and the box, which had holes drilled in it to help it sink, was thrown into the water.
Tahiata's co-accused Trent Michael Thrupp, Tepuna Tupuna Mariri, Webbstar Latu, Stou Daniels, Davy Malu Junior Taiao, Ngatokoona Mareiti and Waylon Ngaketo Cowan Walker are also facing a committal hearing over the murders.
During cross-examination on Tuesday, Tahiata's laywer Ben Power questioned a homicide detective involved in the investigation.
Detective Senior Constable Christopher Kidd said Tahiata became emotional while in custody and offered to reveal where the bodies had allegedly been hidden.
"I did it. I killed them," he said Tahiata told him.
Tahiata allegedly added: "I can show you where they are".
The court heard the confession wasn't recorded but that Det Kidd has provided a statement about it.
About an hour into Tuesday's hearing Tahiata and Thrupp were committed to face trial in the Brisbane Supreme Court.
A date is yet to be fixed.
All accused murderers are in custody and the hearing continues.