In July 1992, Robert Napper stabbed Rachel Nickel in front of her 2-year-old son. In November 1993, he broke into the home of Samantha Bisset and stabbed her to death.
Richard Roszkowski gunned down three people in Connecticut in 2006, including a nine-year-old.
John Wayne Gacy murdered 33 boys and young men during a six-year period in the 1970s. He hid the bodies of his victims in the walls of his suburban home.
Ian Huntley abducted two ten-year-old schoolgirls, Holly Wells and Jessica Chapman, murdered them and tried to burn the bodies.
For one week in 2016, Stefano Brizzi stored the body of a policeman in his flat in central London. Taking inspiration from the TV show "Breaking Bad," he tried to dissolve the body in his bath tub.
The story of a terrifying killer who snatched away the lives of four victims.
In 2003, Kenneth Regan and William Horncy murdered a millionaire and his young family. The killers wiped out three generations of the Chohan family, including two young children.
In 2007, single mother of three Paige Birgfeld went missing.
Railway Killers John Duffy and David Mulcahy killed three women and raped many more across a four-year period in the early 1980s.
Wayne Adam Ford is an American serial killer who strangled and dismembered three of his four victims.
Jane Longhurst vanished after making a plan to go swimming with her friend's boyfriend.
Beverley Allitt killed four children and attempted to murder nine more while working as a nurse at Grantham and Kesteven Hospital in Lincolnshire in 1991.
45-year-old Stephen attempted to kill his parents and nephew in a car crash. After the plan failed, the ruthless killer mercilessly executed his elderly parents with a shot gun.
Paul Runge raped and killed seven people in Chicago. Police lacked evidence to arrest him despite suspicions.
Peter Sutcliffe, also known as The Yorkshire Ripper, was convicted of killing thirteen women and attempting to murder seven others.
Danilo Restivo murdered two women nine years apart: sixteen-year-old Elisa Clapps in Italy and Heather Barnett in Bournemouth.
Keith Jesperson, known as the 'Smiley Face Killer,' brutally killed at least eight women across five American states in the early 1990s.
Ali Qazimaj is an Albanian conman who brutally murdered an elderly couple in 2016.
Over a 25-year career of murder, Richard Biegenwald killed at least six people.
Fred and Rose West raped, tortured and killed young women in their house of horrors, including their own daughter.