Queensland's Attorney-General has written to the state coroner asking him to hold an inquest into the 1973 firebombing of Brisbane's Whiskey Au Go Go, in which 15 people died.

The announcement comes a day after convicted killers Vincent O'Dempsey and Garry Dubois were sentenced to life in jail for the deaths of Brisbane mother Barbara McCulkin and her two daughters, Vicki and Leanne, in 1974.

In court, Justice Peter Applegarth said it was clear Barbara McCulkin knew enough about each of the pair's roles in night club bombings at the time for them to want to silence her.

Their trials heard she was targeted because she believed they were directly involved in the Whiskey Au Go Go firebombing in the CBD suburb of Fortitude Valley.

Queensland Attorney-General Yvette D'Ath said there was no doubt of the "significant public interest in getting answers".

"Given recent events, witnesses who have previously not been willing to come forward, might now be willing to provide new information that will give us those answers," she said.

"I had been awaiting the outcome of recent court proceedings, and will now write to the state coroner instructing him to hold an inquest into the Whiskey Au Go Go case."

The fire at Whiskey Au Go Go was at the time Australia's largest mass murder. ( ABC News )

Speaking in Townsville, Queensland Premier Annastacia Palaszczuk said it was hoped an inquest into the fire would provide some closure on the case.

"The Whiskey Au Go Go tragedy is etched in the memory of many Queenslanders — we should take this opportunity to find any answers that we can," she said.

"I think a lot of people want closure and this is the right steps that the Attorney-General has made."

The firebombing at Whiskey Au Go Go in the early hours of March 8, 1973, was at the time Australia's largest mass murder.

John Andrew Stuart and James Finch were eventually charged over the firebombing and later found guilty.