Updated August 22, 2018 15:44:51

Photo: Kathleen Folbigg was convicted of killing her four children. (Mick Tsikas: AAP)

New South Wales Attorney-General Mark Speakman has announced there will be an inquiry into the convictions of Australia's worst female serial killer, Kathleen Folbigg.

Folbigg was found guilty by a jury in 2003 of the murder of her three young children and the manslaughter of another.

Governor David Hurley has appointed the former chief judge of the District Court, the Hon Reginald Blanch AM QC, to conduct the inquiry.

"I have formed the view that an inquiry into Ms Folbigg's convictions is necessary to ensure public confidence in the administration of justice," Mr Speakman said today.

Mr Speakman said the "immensely difficult decision" had been explained to Folbigg's former husband Craig.

He apologised for the "renewed distress and pain" the family will endure throughout the probe.

"Ultimately, my job as Attorney-General is to ensure public confidence in the administration of justice in NSW," Mr Speakman said.

Folbigg was initially sentenced to 40 years in jail but it was reduced to 30 on appeal, with a non-parole period of 25 years.

Mr Speakman said she would remain incarcerated during the course of the inquiry, which is estimated to take between six and 12 months.

The matter may be forwarded to the Court of Criminal Appeal if the probe finds there is reasonable doubt around Folbigg's convictions.

Photo: Kathleen Folbigg was convicted of killing her four children, including Laura (pictured). (Supplied)

Over a 10-year period from 1989, Kathleen and Craig lost four children in similar circumstances.

The deaths were all discovered by Folbigg.

Two were put down to sudden infant death syndrome (SIDS), but a pathologist became suspicious during an autopsy on one child, Laura, who lived until she was 19 months old.

During her trial, the crown argued Folbigg had smothered her children and relied on circumstantial evidence that she was a stressed mother. The court also heard details of incriminating diary entries.

She has always maintained her innocence.

In 2013, her lawyers presented a report by forensic pathologist Professor Stephen Cordner, who re-examined medical evidence.

He concluded the deaths of two of the children — Caleb and Sarah — were properly categorised as SIDS incidents.

The death of Folbigg's son Patrick was said to be related to epilepsy, while Professor Cordner also said there were no signs of smothering in any of the incidents.

Topics: courts-and-trials, law-crime-and-justice, sydney-2000

First posted August 22, 2018 14:52:29