Title changed from "The Barking Murders" to Four Lives to honor the victims. Additionally, the creators thought the previous title might sounded too much like a conventional police procedure drama.
Filmed in early 2019 but was delayed by an ongoing inquest into the four deaths and how the police handled them; this didn't conclude until December 2021.
Sheridan Smith and Robert Emms previously worked together on ITV drama "Cleaning Up" (2019).