Vincent O'Dempsey has been found guilty of murdering Barbara McCulkin and her two daughters, 43 years after they disappeared from their Brisbane home.
The 78-year-old had pleaded 'not guilty' to taking McCulkin and daugthers Vicki, 13, and Leanne, 11, from their Highgate Hill home on the night of January 16, 1974 and murdering them.
The bodies of the three women have never been found, in what became one of Queensland's most notorious cold cases.
The Brisbane Supreme Court jury deliberated for four hours on Thursday before handing down the findings on Friday, Nine News reports.
It's believed O'Dempsey abducted McCulkin and her daughters from their family home and took them to bushland near Warwick, 130km south-west of Brisbane, where they were killed.
The prosecution argued O'Dempsey, who knew the McCulkins, wanted Barbara silenced because he was afraid she would implicate him in two Brisbane nighttime fire bombings.
During the trial, three witnesses separately told the Supreme Court that O'Dempsey had confessed to the killings.
Former friend Warren McDonald and O'Dempsey were involved in growing cannabis on McDonald's property when he brought up the McCulkin family in conversation.
"He talked about the McCulkins and he said to me he killed the McCulkins," McDonald told the court.
"I said 'aren't you worried about getting caught?' He said 'they'll never catch me because they'll never find the bodies'."
The now 78-year-old O'Dempsey sat stony faced and did not flinch as the verdict was handed down, according to the ABC.
In a separate trial late last year, co-accused Garry Dubois was found guilty of the rape and murder of Vicki and Leanne and the manslaughter of their mother.
Both men will receive their sentence at a later date.
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