Mark Hobson walked out on his happy family with no explanation on New Year's Day. Five years later he went on a murder spree, killing his girlfriend, her sister and an elderly couple. Criminologists and psychologists try to decode this enigma.

A look at the crimes of Andrzej Kunowski, a man so vicious he was nicknamed the Beast after raping and murdering a 12-year-old girl in 1997.

A case highlighting the dangers of online grooming, 14-year-old Breck Bednar was lured to a London flat before being killed by a fellow teenager.

The story of 30-year-old church warden Ben Field, who was jailed in 2019 for the murder of Peter Farquhar, 69, whom he duped into a fake relationship and persuaded to change his will, before drugging him with a cocktail of pills

A look at the 21-year-old killer who brutally took the life of British student Matthew Pyke, after developing an obsessive infatuation with his girlfriend.

He decided to become a serial killer and brutally snatched away the lives of five innocent men. This is the story of the calculated murderer.

A look at the convicted double-murderer responsible for taking the lives of Becky Godden-Edwards in 2007 and Sian O’Callaghan in 2011.

A look at the welsh serial killer known to some as The Wildman, who got four life sentences for a string of gruesome murders and sexual assaults.

Harold Shipman: A profile of one of the most prolific serial killers in history. With an estimated victim-count of 250, what drove his horrific crimes?

The story of 21-year-old Anthony Arkwright from South Yorkshire, who in 1988 went on a killing spree in which he murdered three people - including his own grandfather.

Profiling the Italian killer, jailed for murdering and mutilating his Bournemouth neighbour, Heather Barnett, in 2002.

A profile of serial killer Dale Cregan, who was sentenced to life in prison after the senseless murders of two men and two police officers in 2012.

The story of Hartlepool man Arthur Hutchinson, who achieved notoriety in 1984 when he broke into a Sheffield home and took the lives of three family members in a senseless killing.

Peter Moore, the killer dubbed 'The Man In Black', a murderer who took the lives of four innocent men for fun.

A look at the brutal murderer, dubbed The Beast of Manchester, who claimed the lives of three teenage girls in the 70's.

New. Roy Whiting: A profile of child killer Roy Whiting, the convicted sex offender who abducted and murdered eight-year-old Sarah Payne.

A chilling look at a man responsible for one of the biggest police investigations in Bristol - the cold-blooded murder of Joanna Yeates.

A look at the Scottish serial killer who preyed on young girls between the ages of five and 11 throughout a six-year killing spree.

A profile of the man responsible for the cold-blooded murder of two teenage girls in 1977, known as the World's End Murders.

An examination of Mick Philpott, the notorious Derby father of 17 who murdered six children, five of them his own, when he set his own home on fire.

The story of Raoul Moat, who shot his ex-girlfriend, her new lover and a policeman, leading to the largest manhunt in modern British history.

A profile of former aspiring model Tracie Andrews, who stabbed her fiance 42 times in 1996 and then blamed the attack on a fictional road rage assailant.

In 2012, April Jones disappeared from outside her home in Wales, never to be seen again. Her abductor, and murderer, was found to be Mark Bridger.

Robert Napper: Known to some as The Plumstead Ripper, he was convicted of two murders, but his victim count is actually estimated to be much higher.

The story of Steven Grieveson, the so-called `Sunderland Strangler', who murdered four teenage boys before his capture.