The story of Sir Alec Jeffreys' discovery of DNA fingerprinting and its first use by DCS David Baker in catching a double murderer.

DCS David Baker headed up the investigation into the brutal murders of two Leicestershire schoolgirls between 1983 and 1987. Only a few miles away, Dr Alec Jeffreys, was a scientist at Leicester University who, on 10 September 1984, invented a remarkable technique to read each individual's unique DNA fingerprint. When a local teenager admitted to one of the murders but not the other, Baker asked Jeffreys to analyze the DNA evidence left at the crime scenes. Both men were shocked to discover that the teenager was innocent, his confession false. DCS Baker then took the extraordinarily brave step to launch the world's first ever DNA manhunt, testing over five thousand local men to track down the killer.—dvd