Kathleen Folbigg was found guilty of three counts of murder and one count of manslaughter. She became known as Australia's "worst female serial killer".
There was no evidence of smothering or injuries to the children. The trial focused on circumstantial evidence, mainly Folbigg's diary, in which she wrote that "guilt about them all haunts me" and detailed her struggles with motherhood.
Folbigg's conviction was mainly based on the reasoning that the likelihood of four children from one family dying of natural causes is so unlikely as to be virtually impossible.
With advances in understanding of genetic disease and a drop in cost of genetic testing, some scientists were eventually able to carry out a study which showed that the woman had a rare mutation, which had also been passed down to all her children which died, but not to her two children that did not die.
She was released in June 2023, after having spent 20 years in prison.
They had a rare mutation in a gene called CALM, which encodes the protein calmodulin.
The mutation is believed to affect only 1 in 35 million people, and there are only 135 persons in the world who are known to have it.
The mutation causes cardiac arrythmia, which can lead to a heart attack.
The two girls both had respiratory issues prior to their deaths.
An Extremely Rare Mutation Landed a Woman in Prison For Murder, June 9, 2023, Felicity Nelson, ScienceAlert.com