After a top-secret investigation into Stephen Lawrence's murder (using 'James Bond' tactics including ‘bugged’ golf buggies, a spy helicopter and a daring undercover operation) failed to bring justice for the teenager, police reassessed the forensic evidence from the first weeks after Stephen was murdered, and found a crucial clue: a tiny flake of dried blood. Acclaimed crime writer Stephen Wright talks to police, politicians, and the forensic scientist whose team also found a breakthrough blood trace on a jacket. 

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Producer: Rosie Gillott