Dark Angel: the gruesome true story of Mary Ann Cotton, Britain's first serial killer

Britain’s first serial killer ended her 20-year poisoning spree in 1873, thrashing around at the end of a hangman’s rope in Durham Jail. When the gallows trapdoor opened, Mary Ann Cotton dropped just two feet, a fall insufficient to break her neck. The hangman leant over and pushed down on her shoulders to hasten strangulation. She took several minutes to die.