In 2016, a mum of three and a wannabe serial killer became two of Australia's most calculated female murderers.

Dr Kari Pitts is a forensic chemist and trace evidence expert, who has worked on over 300 criminal cases, including homicides, violent assaults, arson, and fatal hit-and-runs.

In this episode, Kari explains how a dyed blue hair and some carpet helped convict Perth's female thrill kill pair. Kari also tells host Kathryn Fox about an initiative she pioneered with the WA Police, that has so far assisted in over 150 sexual assault investigations.

If you're in Australia, information and support for anyone affected by domestic, family, and sexual violence is available at 1800 RESPECT (1800 737 732). If you or someone you know is in crisis, contact Lifeline on 13 11 14. If you or someone you know is in immediate danger, call 000.

If you're outside of Australia, visit this link for a list of support services.

See omnystudio.com/listener for privacy information.