Serial killer Kathleen Folbigg was convicted of murdering her 4 babies. Now scientists back her pardon bid 6 May, 2021 07:47 AM 6 minutes to read Kathleen Folbigg leaving Maitland Court after being refused bail in 2004. Photo / Getty Other Nearly two decades after an Australian woman was convicted of killing her four children, dozens of scientists are backing the claim that they may have died of natural causes. Australian law says Kathleen Folbigg is one of the nation's worst female serial killers who smothered her four children over a decade. But a growing number of scientists say she could be the victim of a tragic miscarriage of justice.