In the first episode, when DCS David Baker first meets Alec Jeffreys on the steps, the real Alec Jeffreys walks up the steps and passes them.
The actual Crimewatch appeal for the murders are used in part 2.
Based on a true story.
The laboratory is a real Chemistry lab at the old Dagenham site of pharmaceutical company Sanofi, which was closed in 2013.
The Blooding: The True Story of the Narborough Village Murders (1989) written by Joseph Wambaugh is a non-fiction account of this event.