The Beast of Birkenhead: 5. Unknown Male One

Recorded on the day of Peter Sullivan’s appeal as judges consider DNA evidence unavailable in 1987.

As the new evidence points to an unknown male, decades-old evidence crumbles under scrutiny.

The court delivers its decision leaving one devastating truth intact: Diane’s killer has not been found.

Presenter: Olivia Graham. Producers: Kate Bissell, Gemma Maull and Olivia Graham. Sound Design and Music Composition: Phil Channell. Mixing: Ivan Eastley. Story Consultants: Neil McCarthy, Jack Kibble-White and Kirsty Williams. Online Producer: Rachael Smith. Development was by BBC Audio Scotland and BBC Merseyside. Executive Editors: Gillian Wheelan and Ben Anderson. Commissioning Editor: Alistair Miskin.

There’s graphic descriptions of violence in this series. For details of help and support in the UK, visit bbc.co.uk/actionline.