A Brisbane jury has found Garry Dubois guilty of the 1974 murders of sisters Vicki and Leanne McCulkin and the manslaughter of their mother Barbara.

Dubois, 69, has also been found guilty of raping the two girls before killing them, as well as deprivation of liberty.

Their bodies have never been found.

After a three-week trial in the Supreme Court, the jury took almost three days to hand down its verdict.

Dubois was silent as the verdicts were delivered. He briefly spoke to his wife and waved to his supporters as he was taken from the dock.

He had pleaded not guilty to all charges, but several witnesses told the court they saw Dubois at the McCulkins’ Highgate Hill house on the night the victims disappeared in 1974.

Defence barrister Dennis Lynch had told the court in his closing statement that it was possible they were murdered by father and husband Billy McCulkin.

He had also attacked the reliability of key prosecution witness Peter Hall, who told the court Dubois confessed to him in the days after the family disappeared.

“It’s abundantly clear that Peter Hall has told lies, it’s abundantly clear that he continued to lie,” Mr Lynch told the court.

“His reason for telling a lie was to save his own neck because it had been made painfully obvious to him that he wasn’t believed. He simply fell into line.”

Dubois’ legal team said it would investigate the chances of an appeal, and would make a decision in the next month.

The McCulkin family did not speak outside court, but stood beside Detective Inspector Mick Dowie who talked to the media on their behalf.

“On behalf of the investigation team, and more importantly the Ogden and McCulkin families, we wish to advise that we welcome the verdicts of guilty delivered today by the jury,” he said.

Dubois’ wife Jan, who has been in court for the entire trial, walked away without comment.

Dubois ‘spoke in gruesome detail’ about murder

Mr Hall told the trial he and Dubois used to hang out and engage in criminal activity together.

He said he and Dubois had been involved in the 1973 firebombing of the Torino nightclub, along with two other men.

The court heard that on the day the three went missing, Dubois asked Mr Hall if he wanted to come to the McCulkins “to have sex with the girls”.

Mr Hall said he declined.

He said Dubois had spoken in gruesome detail regarding Barbara McCulkin’s murder.

Co-accused Vincent O’Dempsey will face a separate trial next year over his alleged role in the McCulkin killings.

Dubois faces a mandatory sentence of life behind bars, but a date has not yet been set for sentencing.

-ABC