S1, E3: In the last episode of the series unlocking the secrets that finally solved some of Britain's most controversial murder cases, the programme looks at the killing of Stephen Lawrence. The racist murder of Stephen in southeast London in 1993 remained unsolved for more than a decade after a series of failures by police - that is, until world-leading forensic scientist Dr Angela Gallop and her team were brought in by a new investigation to look again at the evidence.