On 9 January 1986, 21-year-old florist Diane Sindall was brutally murdered in Birkenhead, Merseyside. She was found stabbed and sexually assaulted in a shocking frenzied attack.

Peter Sullivan was wrongfully convicted of her murder and spent 38 years in prison. In 2025, new DNA evidence finally cleared him — one of the longest miscarriages of justice in British history. Yet nearly 40 years later, the real killer has still never been caught and remains free.

In this deep-dive documentary, we examine the full timeline, the original flawed investigation, the horrific crime scene, how Peter Sullivan was convicted on weak evidence, the long fight for justice, and the current hunt for the real killer with a £20,000 reward still active.

If you're enjoying these thorough true crime documentaries, please follow Crimes That Haunt Us and leave a rating — it helps more than you know.

Crimes That Haunt Us – respectful, in-depth documentaries on the UK’s most disturbing unsolved cases.

(00:00) The Haunting Case of Diane Sindall

(1:03) Who Was Diane Sindall?

(03:37) The Day of the Murder

(4:54) Another Girl is Attacked First

(5:18) Diane Breaks Down

(6:27) Diane & Her Killer Seen Arguing

(7:32) Murder Investigation is Launched

(11:02) Evidence Found Burning

(16:00) Mr X is Arrested

(18:15) Peter Sullivan is Arrested

(21:05) Sullivan Stands Trial

(24:43) Peter Sullivan is Found Guilty

(27:50) Sullivan is Acquitted