She was once dubbed 'Australia's worst serial killer', after the deaths of her four children. 

But now, Kathleen Folbigg is a free woman, after spending two decades in jail. 

In a miscarriage of justice case reminiscent of the wrongful conviction of Lindy Chamberlain, the NSW Attorney-General has pardoned the 55-year-old after new scientific evidence emerged. 

Today, ABC Background Briefing reporter Rachael Brown on Kathleen Folbigg's freedom and what it says about the judicial system. 

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Rachael Brown, reporter, Background Briefing, ABC Radio National and ABC listen app