1. The Fentanyl Killer

Luke D'Wit tricked his millionaire neighbors into thinking he was a harmless IT geek before poisoning them so he could take over their business. His harrowing call to police gave detectives their first clues in bringing the poisoner to justice.

3. The Killer Chemist

Mitesh Patel strangled his wife in order to claim insurance and start a new life with his lover. After ransacking their home to make it look like a burglary gone wrong, he made a tearful call to emergency services, unknowingly leaving clues as he spoke.

4. The Microscopic Mistake

David and Ann-Marie Pomphret seemed a close and loving couple. When Ann-Marie is found battered to death, a distraught David calls police. Forensic scientists detect microscopic blood cells on his unwashed socks and the truth is revealed.

5. Killer in the Woods

Andrew Pearson kidnapped his ex-partner Natalie Harker before strangling, drowning and sexually assaulting her. In a distraught call to police, he then tried to claim her death was an accident but inadvertently left a series of clues as he spoke.

6. An Oscar-Worthy Performance

Flames engulf a village workshop, killing owner David Twigg. Police hunt for two masked intruders, who were reported in a call by David's partner, Julie Dixon. Later, at the trial, the judge says Dixon’s call is worthy of an Oscar nomination.

7. The Killer Next Door

Ex-Commando and trained killer stabbed his two neighbors to death after a long-running parking dispute. He claimed his actions were due to a mental breakdown caused by his Army service. But his cool and calm call to police told a different story.

8. A Deadly Trap

It sounds like a routine call to police, but it's a deadly trap. The caller is a killer who’s vowed vengeance on the police. When two unarmed female officers turn up to investigate, they are brutally murdered by one of Britain’s most wanted fugitives.