Notorious killer took own life in secure cell: coroner
A man convicted of murdering a mother and her daughters half a century ago committed suicide in a secure prison unit, a coroner said.
Garry Reginald Dubois, 74, was found dead in his cell during a count at 4.45am on June 7, 2021, at Queensland Maryborough Prison, north of Brisbane.
Dubois and Vincent O’Dempsey were convicted in November 2016 of the 1974 murders of Barbara McCulkin, 34, and her daughters Vicki, 13, and Leanne, 11.
Evidence at the trials of Dubois and O’Dempsey led to the reopening of the investigation into the 1973 firebomb attack on the Whiskey Au Go Go nightclub in Brisbane, which killed 15 people.
At their trial it was stated that the murders may have been motivated by fear that Ms McCulkin would try to implicate them in the firebombing of the nightclub.
Dubois died before he could testify at the inquest.
Assistant State’s Attorney Stephanie Gallagher announced her findings following a May 2025 hearing in Dubois’ death.
Dubois died in his cell in a secure unit from self-inflicted injuries as well as heart disease and medical treatment to thin his blood.
Ms Gallagher found that he had been held in pre-trial detention since October 2014.
“Mr Dubois was classified as a protection prisoner due to the high-profile status of his crimes and was held in Cell 41 on level 2 of Secure Unit 2, the protection block,” Ms Gallagher said in her findings. he said.
Ms Gallagher accepted Dubois did not show signs of being at risk of self-harm or suicide when he purchased items from the prison canteen which he used to take his own life six weeks later.
“There is no evidence to suggest that his access to items should have been restricted at that time,” Ms Gallagher said.
Acting Commissioner Eloise Hamlet said the Queensland Correctional Service strives to strike a balance between protecting human life and treating prisoners humanely while providing basic hygiene items that could be used for self-harm.
The Corrective Services incident report recommended that no disciplinary violations or criminal charges be incited as a result of Dubois’ death.
Dubois and O’Dempsey were jailed for life for murdering McCulkins in woodland near Warwick on the night of January 16, 1974, after kidnapping him from his home in Brisbane.
Dubois was convicted of raping and murdering sisters Vicki and Leanne.
He was convicted of a lesser charge of manslaughter over their mother’s death.
Ms Gallagher saw no need for further advice given Dubois’ death and did not request a response from the Queensland government.
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