O'Dempsey not testifying in his defence

Sarah Motherwell

Vincent O'Dempsey has chosen not to give evidence in his trial for the alleged Brisbane cold case murders of Barbara McCulkin and her two daughters.

Since pleading not guilty to their murders, the 78-year-old has sat silently in the Brisbane Supreme Court dock for three weeks as more than 50 witnesses testified over his alleged involvement in their disappearance.

Mrs McCulkin and her children Vicki, 13, and Leanne, 11, were last seen at their Highgate Hill home on January 16, 1974.

The court has heard two men, believed to be O'Dempsey and Garry Dubois, were seen at the family's property that same day, as well as a distinctive orange Charger like the one O'Dempsey owned.

O'Dempsey is alleged to have confessed to friend Warren McDonald and former fiancee Kerri Scully separately he killed the McCulkins.

A prison informant, who cannot be named for legal reasons, also testified that during one of their regular conversations in February this year O'Dempsey denied killing children but said their mother "had to be dealt with".

The informant also claimed O'Dempsey discussed plans to "get at" Mr McDonald.

"He was trying to arrange to get at him," he said.

"He knew what time he left for work, which road he took, which roadhouse he stopped at for breakfast ... the number of his house."

Prosecutor David Meredith and defence barrister Tony Glynn are due to give their closing arguments on Monday, with the jury expected to begin its verdict deliberations later in the week.