
Examining some of the most dangerous and prolific murderers in the UK and worldwide.

A look at the London serial killer Dennis Nilsen, who murdered at least 12 men before being caught.

When Tia Sharp disappears, Stuart Hazell helps police search for her, but in reality he had murdered the 12-year-old.

Peter Tobin raped and murdered a student in 2006, and investigations linked him to two more murders.

In 1987, Michael Ryan killed 16 people in Hungerford, Berkshire, before turning the gun on himself.