The New South Wales Director of Public Prosecutions has announced he will not appeal against a decision to acquit Sydney man Jeffrey Gilham of the stabbing murder of his parents.

On Monday the state's Court of Criminal Appeal ruled Mr Gilham be acquitted over the 1993 murders of Helen and Stephen Gilham in their home in Sydney's south at Woronora.

The three-judge panel was split in its decision, with Justice Peter McClellan believing Mr Gilham should face a retrial.

DPP Lloyd Babb SC has now directed that there will be no appeal in the matter.

Mr Gilham has always maintained his brother Christopher Gilham committed the murders and tried to burn down the family home.

Jeffrey Gilham pleaded guilty to his brother's manslaughter in 1995 and was given a five-year good behaviour bond for it.

He said he killed his brother by stabbing him 17 times after discovering the crime scene.

Mr Gilham was convicted of murdering his parents in 2009 and given two life sentences, but his release was ordered in December last year after issues were raised about forensic evidence presented to the jury.