Mary Ann Cotton
In 1871, 40-year-old Mary Ann Cotton and her husband, 39-year-old Frederick moved into a home in County Durham, with his two stepsons and her 7-month-old baby. Two months later frederick died of gastric fever and one of Mary's lovers, Joseph Natrass moved in.
In the space of a month Belle's baby, Natrass and Frederick's son all died in the house. On the 12 July 1872 the other son of Frederick died, all the deaths caused suspicion and a neighbour went to the police.
A post mortem was carried out on the stepson and it revealed him to be poisoned with arsenic. The bodies of the other dead were exhumed and they showed that arsenic was the cause of death. Mary was arrested and charged with the murder of her stepson. She went to trial in March 1873, claiming that they were accidentally killed by arsenic contained in wallpaper, but the prosecution had evidence that she had purchased arsenic. Mary Ann Cotton was found guilty and sentenced to death.
Cotton was suspected of the murders of 14 people, in her older life twenty one people close to her died. Her motive was gain, as she would marry, kill and collect the insurance money, then repeat it again. She was hanged in Durham prison on 24 March 1873.