A woman who was dubbed Australia’s “worst female serial killer” after she was found guilty of killing four of her children has received the backing of dozens of scientists who, nearly two decades later, say the children may have all actually died of natural causes. Kathleen Folbigg has been behind bars for the past 18 years after her May 2003 conviction, when she was found guilty on three charges of murder and one of manslaughter. The charges stem from a string of deaths of her children: Her first child, Caleb, died a mere 19 days after being born in 1989. Her second one, Patrick, died in 1991 at 8 months old, followed by her third child, Sarah, who died two years later at 10 months old, and then the fourth child, Laura, who passed away in 1999 when she was 19 months. During Folbigg’s seven-week trial, prosecutors argued that it was simply impossible for all children to have died naturally, alleging that Folbigg had simply become fed up with the children and smothered them.

But 90 scientists and medical experts from around the world have now thrown their weight behind a petition seeking Folbigg’s pardon, citing recent discoveries in genetic research that point to all four of the children being at high risk of sudden death. Research by more than two dozen scientists published last year pointed to a genetic mutation discovered in the two Folbigg daughters that causes abnormal heartbeats and can lead to sudden death. The same scientists also said they uncovered a variant of a gene in the boys that had been known to send mice into fatal epileptic fits. Eighteen years into her 30-year sentence, Folbigg has now filed a petition with the New South Wales state governor seeking a pardon “based on significant positive evidence of natural causes of death” in the children’s deaths.