Kathleen Folbigg is seen as Australia's worst female serial killer. Now she might be getting a second chance.

With AAP

Warning: This post deals with the deaths of four young children.

Kathleen Folbigg is considered to be Australia’s worst female serial killer.

In 2005, she was jailed for the murders and manslaughter of her four infant children.

Kathleen and Craig Folbigg had their first child, Caleb Gibson, on February 1, 1989. Just 19 days later, on February 20, Kathleen said she found her son dead in his cot, court documents say. His death was attributed to Sudden Infant Death Syndrome (SIDS).

In June 1990, their second child, Patrick Allen was born. One morning in October that year Craig said he awoke to sound of his wife screaming and rushed over to find her standing by his cot and the little boy unresponsive. Craig managed to revive his son until an ambulance arrived, taking him to hospital. Doctors couldn’t determine what had caused Patrick to stop breathing, but diagnosed him with epilepsy.

On February 13, 1991, Craig got a call from his wife at work. “It’s happened again,” she screamed. According to court documents the father arrived at the same time as paramedics and found his son lying unresponsive in his cot. Patrick was pronounced dead at hospital, with a doctor determining he had suffered cardiac arrest – though a later autopsy could not find what had caused this.

In October 1992 the couple’s third child, Sarah, was born. In August 1993, Craig was again awoken by his wife’s screaming to find his child unresponsive on her bed. An autopsy found that Sarah had small cuts near her mouth and that injuries to her lungs were consistent with “asphyxiation caused by the application of mild force” – yet her death was determined to be caused by unknown natural causes, SIDS.

Laura was born in August 1997 and made it to March 1, 1999, before her sudden death while her mum was alone with her around lunchtime. Doctors found that the 19-month-old had suffered with myocarditis, inflammation of the heart muscle, but did not determine it to be the cause of her death.

In 2003, Kathleen, then 35, was found guilty of Patrick, Laura and Sarah’s murders, and Caleb’s manslaughter. Kathleen was the first at the scene in all four cases.

Lawyers for Folbigg lodged a petition in 2015, casting doubt on some of the evidence that led to her conviction.

NSW Attorney-General Mark Speakman said he’d formed the view an inquiry into her convictions was “necessary to ensure public confidence in the administration of justice”.

“The distress that today’s decision will cause is something that has weighed on me heavily in formulating this recommendation,” Speakman said.

“Whatever view you take of this case, it is a tragedy beyond imagination that four beautiful children were lost.”

“We did it,” Folbigg’s friend Tacey Chapman told the Seven Network after the review was announced.

“It did take too long but it’s an outcome we’re all very happy for and I’m sure Kath’s going to be very relieved like the rest of us.”

Speakman said the decision was not based on any assessment of Folbigg’s guilt.

“I have spoken with (the babies’ father) Craig Folbigg to explain this immensely difficult decision. I am sorry for the renewed distress and pain he and his family will endure because of the inquiry.”

Mr Folbigg’s brother John said he was frustrated by the decision.

“We’re going to live it again, it’s not nice,” he told the Seven Network.

“As far as we’re concerned 15 years ago we got our answer.”

Former District Court chief judge Reginald Blanch will lead the inquiry.

The inquiry is expected to focus on the evidence or lack of evidence related to whether three or more deaths can occur in a family with no explanation, Speakman said.

It’s expected to take six to 12 months.

If Blanch finds that there is a reasonable doubt as to Folbigg’s guilt he may refer the matter to the Court of Criminal Appeal for further consideration.