A $1 million reward is being offered by NSW Police for information about the murders of three Aboriginal children in Bowraville 30 years ago.

Four-year-old Evelyn Greenup, Clinton Speedy-Duroux, 16, and Colleen Walker, 16, disappeared from the northern NSW town over a five-month period from September 1990.

NSW Police Commissioner Mick Fuller and the state’s Attorney-General Mark Speakman on Wednesday announced the reward for information on the murders had increased from $250,000 to $1 million.

“The increased reward forms part of our commitment to providing justice – firstly to the victims and their families – but also to the entire Bowraville community,” Mr Fuller said.

The murders were originally investigated separately before being linked by the homicide squad.

A man, who can’t be named for legal reasons, was acquitted of Clinton’s murder in 1994 and of Evelyn’s murder in 2006.

Colleen Walker 16, Clinton Speedy-Duroux, 16, Evelyn Greenup, 4, were murdered at Bowraville in the 1990s.

The government in 2018 unsuccessfully argued in the NSW Court of Criminal Appeal that there was fresh and compelling evidence – related to the disappearance of Colleen – which justified overturning the two acquittals and a new single trial on three murder charges.

The High Court refused to grant special leave to the NSW government to appeal the decision.

In 2019, NSW Greens MP David Shoebridge pushed to change the state’s double-jeopardy laws after the High Court decision.

Under the laws revised in 2006, a person can be tried for the same crime for which they’ve previously been acquitted only if there’s fresh and compelling evidence.

Mr Shoebridge sought to amend the law to facilitate a retrial of the suspected killer of three Aboriginal children in Bowraville in the early 1990s.

But, a NSW upper house inquiry in 2019 found the bill would impact on too many unrelated parts of the criminal justice system and should not proceed.

The committee argued a separate proposal by UTS’ Jumbunna Institute of Indigenous Education and Research – reflecting the current English and Welsh approach – should be considered.

That approach would give the court greater freedom to consider the interests of justice in its decision to grant a retrial.

On Wednesday, Mr Speakman said the NSW government would not be implementing the proposal.

“The impact of the government’s decision on the Bowraville families has weighed heavily on me. The decision will bitterly disappoint them. For that, I am very sorry,” he said.

-AAP