Dubois won't testify in McCulkin trial

Garry Dubois has declined to give evidence at his trial for the murders of Barbara McCulkin and her two daughters in 1974.

Dubois, 69, has been on trial in the Brisbane Supreme Court for nine days charged with raping and murdering siblings Vicki and Leanne McCulkin, and killing their mother.

He did not testify in his defence at the conclusion of the prosecutor's case on Thursday.

The jury are expected to begin deliberating their verdict in the middle of next week after closing submissions from the lawyers and judge.

It is alleged Dubois and another man, Vincent O'Dempsey, drove Mrs McCulkin and her daughters from their Hamilton Hill home to bushland where they were killed.

The trio were last seen on January 16, 1974 and their bodies have never been found.

O'Dempsey is due to stand trial in the same court next year.

Dubois' trial has heard he told key witness Peter Hall he raped one of the girls but O'Dempsey killed the trio.

Information Mrs McCulkin had about Dubois and O'Dempsey's involvement in the 1973 fire at the Fortitude Valley club Torino may have been the motivation to kill her, the court has heard.

Paul Dubois testified on Monday his younger brother denied to him that he was involved in the McCulkins' disappearance and claimed Mrs McCulkin had been blackmailing O'Dempsey.

"He (Garry) said 'Vince told me the kids weren't meant to be there'," Mr Dubois said.

Dubois's former neighbour Trevor McGrath said Dubois told him in 2009 the cops kept looking into him every five years but he'd be right because "they'd never find the bodies".

The trial will continue on Monday.