One of Queensland’s most enduring murder mysteries has taken another dramatic twist with sensational new claims the victim’s husband made a deathbed confession.

Police are investigating a revelation that soon before Billy McCulkin’s 2011 death he confessed to murdering his former wife Barbara and their two daughters in the 1970s.

Mrs McCulkin, 34, and daughters Vicki, 13, and Leanne, 11, vanished from their Brisbane home in January 1974, sparking one of Queensland’s most baffling murder mysteries.

• John Laws ridicules abuse victim on air 
• Pregnant woman’s baby stolen from womb

Two men, Gary Reginald Dubois and Vincent O’Dempsey, were charged with the murders last October, more than 40 years later.

However, it was revealed in the Brisbane Supreme Court that Mr McCulkin’s most recent wife has come forward to police with claims he confessed to murdering the trio and burying their bodies.

The claims were made during an unsuccessful bail hearing for 68-year-old Dubois on Friday.

Dubois’ lawyer, Dennis Lynch, referred to Mr McCulkin’s late wife’s claims in an attempt to highlight the “weak” crown case.

“She has been interviewed by police; that interview has been recorded, and as I understand it, she told the police that he confessed to her shortly before he died,” Mr Lynch said.

But crown prosecutor David Meredith downplayed the claim, saying it was at odds with other evidence.

“Naturally, it is being investigated,” he said.

The prosecution alleges Dubois and O’Dempsey took the McCulkins from their home and drove them to a location, where they were bound and killed by O’Dempsey.

It’s alleged Mrs McCulkin was killed because of her knowledge of who was behind the 1970s arson attacks on the Torino’s and Whiskey Au Go Go nightclubs.

A key witness, who came forward in 2014 and wants indemnity, claims Dubois confessed in 1974 to having been present and having helped bury the bodies.

“I can tell you now they will never find the bodies,” Dubois allegedly told another witness in 2010.

However, Mr Lynch said witness accounts differed.

“It’s a weak case, relying on a more than 40-year-old confession, related for the first time in 2014,” he said.

In the end, Justice Peter Applegarth accepted prosecution fears that witnesses could be subject to intimidation if Dubois is granted bail.

The witnesses are so fearful of intimidation that court documents naming them, which are usually available to the public, were ordered sealed.

– AAP