Forensic scientists showed the BBC how to commit the perfect murder.
Modern forensic science should make it impossible to commit murder and get away with it. But how easy would it be to outfox the detectives if you know what you are doing?
With the help of top forensic scientists, and real-life murder investigations, BBC's Horizon program explored whether it is possible to commit a perfect murder.
Pathologist Dr Richard Shepherd reveals the crucial clues that give away the secrets of a suspicious death.
What is the perfect murder weapon? Poison. It leaves no marks on the body, and the victim may not even realise what has happened until it's too late.