Trace of Evil

This episode explores one of the longest running and most dedicated investigations in modern British history. It tracks the advances in forensic technology that eventually led to the murders being solved, finally giving justice to the victims' families after 37 years.

This episode tells the story of how a most unlikely killer was stopped in his tracks as he embarked on a crime and murder spree, thanks to digital forensics, police work and a good old-fashioned stake-out.

When women start to go missing, the city of Baton Rouge goes into lock-down. Investigators and family members work together to find that illusive trace of evil.

Just as Baton Rouge starts to feel safe they discover a second serial killer is at work. But when he leaves a trace at a scene, the police get an unexpected breakthrough.