Code of a Killer is a two-part British police drama television series which tells the true story of Alec Jeffreys' discovery of DNA fingerprinting and its introductory use by Detective David Baker in catching the double murderer Colin Pitchfork. Filming commenced in late September 2014, and the program aired on the ITV network, beginning on 6 April 2015.The Blooding: The True Story of the Narborough Village Murders (1989), written by Joseph Wambaugh, is a non-fiction account of this event.