A look at the north London serial killer Dennis Nilsen, who murdered at least 12 men before being caught when he began flushing remains down the toilet.

When Peter Tobin was convicted for raping and murdering a Polish student in 2006, further investigation linked him to two more murders.

The Yorkshire Ripper. Examining some of the UK's most prolific killers. Peter Sutcliffe's five-year killing spree claimed 13 victims.

Ian Huntley murdered two 10-year-old schoolgirls in a case that shocked the nation and changed the course of British policing.

The first woman in British history to be given a whole life sentence, Joanne Dennehy's 2013 rampage saw her murder three men and attack two more.

Between them, Fred and Rose West killed at least 12 girls over two decades in Gloucestershire. What fuelled their appetite for murder?

Levi Bellfield was already in prison for killing two women when he was found guilty of murdering schoolgirl Milly Dowler in 2002.

The Suffolk Strangler. Steve Wright brutally killed five women over a six-week period in 2006. He is unquestionably one of Britain's Most Evil Killers.

Nurse Beverley Allitt poisoned 13 children under her care, killing four of them, earning her the nickname "The Angel of Death" from the British media.

The Crossbow Cannibal: A chilling look at Stephen Griffiths, who in 2009 viciously murdered three women - one in blatant view of a CCTV camera.

When Tia Sharpe disappeared, Stuart Hazell helped police search for her. But in reality he'd murdered the 12-year-old schoolgirl.

30 years after the tragedy in Hungerford took place, we recall the events of 19 August 1987 where killer Michael Ryan claimed 16 lives and his own.