Mary Ann Cotton was a prolific serial killer and was deemed as Britain's first serial killer but chances are you have never heard of her and at least the twenty-one murders she has committed. Cotton was also known as the original Black Widow as she killed four husbands, her mother, a friend, a lover, and several children, including her own birth children and seven step-children.

Her weapon of choice in the killings was arsenic poison. Cotton chose arsenic because it was easy to use and easy to come by back them. It dissolved in hot liquid and the symptoms it brought on included diarrhea, vomiting and dehydration. Symptoms common with gastroenteritis, an ailment that was very common back then, especially among poor people. It was commonly called gastric fever. Every one of her husbands that she killed had an insurance policy of about thirty-five pounds, which back then was about six months wages for her husbands who were all coal miners.

Mary Ann Cotton began her killing spree in 1852 and ended in 1872 with her last victim, a step-son named Charles Cotton. His father, Frederick Cotton, Mary's last husband, had died, due to the same circumstances as her previous victims, about a year before. Charles Cotton was deemed to be very healthy until he suddenly succumbed to gastric fever. When Mary Cotton attempted to collect on Charles' insurance policy, the insurance company refused to pay until Cotton's death was examined more closely. Charles Cotton's body was exhumed from his grave and their were traces of arsenic found in his system.

Charges were soon filed and Mary Cotton was arrested for the murder of Charles Cotton. She was convicted of the murder after a three day trial and sentenced to death. Mary Cotton professed her innocence right up to the day that she was killed. Karma stepped in when she was hung at Durham County jail in 1873 as the drop when the trap door opened was too short. She began choking to death and finally died when the hangman pushed down on her shoulders to quicken the choking. Mary Cotton was immortalized in a children's rhyme in Britain:

Mary Cotton, She's dead and she's rotten! She lies in her 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.”