Code of a Killer is a three-part[1] 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.

[3] Set over a nearly four-year period from 1983 to 1987, DCS David Baker leads an investigation into the vicious murders of the two Leicestershire teenage schoolgirls, Lynda Mann and Dawn Ashworth.

Gerard O'Donovan in The Daily Telegraph called the show's version of him a "stock obsessive boffin so wedded to his lab instruments that his marriage was permanently on the brink of collapse".

[10] Julia Raeside in The Guardian wrote, "There are obligatory scenes in which Jeffreys misses a school play and receives a phone call from his wife pronouncing, 'Your dinner’s in the dog.'

"[12] Alex Hardy in The Times was less critical, giving the show four stars out of five and saying that "this fact-based drama managed to balance tragedy with optimism", but added that it "inevitably contained elements of soap".