Mary Cotton was born in North England during the Victorian Period. In Low Moorsley, Tyne & Wear. She was regarded as Britain's Greatest Female Mass Murderer. A 19th Century Children's Ryhme was born out of her famed crimes. It went like this: "Mary Ann Cotton, she's dead and she's rotten. She lies in bed with her eyes wide open. Sing! Sing! Oh what can I sing? Mary Ann Cotton is tied up with string. Where? Where? Up in the air. Selling Black Puddings a penny a pair." The Ryhme may have faded into oblivity, but her crimes remain fresh. Beneath her phony caring exterior, was a cold-blooded killer waiting to strike. Her victims included: 12 of her own children and stepchildren, three husbands, her best friend, and her own mother. Greed was the motive, to collect insurance money. She poisened them with arsenic. The deaths went largely unquestioned and unnoticed, during a time of high infant mortality. Each death was blamed on Gastric Fever. Police methods back then was ancient. Eventually relatives, friends, and the Police became suspicious and did more probing. She was arrested in July of 1872 after the suspicious death of her son, Charles, her very last victim.

The bodies of her other victims were exhumed and toxicology tests revealed positive signs of arsenic poisening in all of them. She was tried and sentenced to hang. Her execution was botched. When the trap door swung open, she wriggled in agony for three minutes, before choking to death. Dead at 40. Which I'm sure didn't phase the victims families and friends, or the restless spirits of her victims.

Source of additional information:
http://murderpedia.org/female.C/c/cotton-mary-ann-photos.htm


** NOTE **
Her remains were later dug up and cremated along with other bodies in the 1990's, then the Ashes relocated.