Sarah Carnell had rewritten her will in her nurse's favor only a short time before the nurse brought her a drink. It was 1862, Carnell was ill and confined to bed, and Catherine Wilson, who lived in the house to look after her, handed over what she called a soothing draught with the words "Drink it down, love, it will warm you." Carnell took a mouthful and spat it out because it burned her mouth. Where the liquid landed it ate a hole through the bedclothes. The glass turned out to hold sulfuric acid, by one contemporary estimate enough to kill fifty people. Wilson fled, and was arrested a few days later.
Tried for attempted murder, she was defended by Montagu Williams, who put it to the jury that the pharmacist who made up the medicine had handed her acid by mistake. The judge, Baron Bramwell, told the jurors plainly that the theory could not stand: acid of that strength, he said, would have heated the bottle until it grew hot or burst long before she carried it to the invalid's bedside. The jury acquitted her anyway, to the astonishment, Williams later wrote, of almost everybody in court.
She did not get far. While the Carnell case was being prepared, police had been working backward through her employment and had exhumed several of her former patients. When Wilson stepped down from the dock a free woman she was arrested again, this time for the murder of Maria Soames, who had died six years earlier. A second indictment, for the murder of Ann Atkinson, was pending against her by the time the Soames case reached a verdict.
The history the police assembled began in Lincolnshire, where she worked as a nurse in Spalding and kept house at Boston for Peter Mawer, a retired sea captain. Mawer suffered from gout and was taking colchicum, the extract of meadow saffron that doctors prescribed for it in small doses and that kills in large ones. He made a will leaving his money to his housekeeper, and died a few weeks later. Because the drug was already part of his treatment, nobody suspected her. Her birth date was never firmly established; she is usually said to have been born around 1822.
She next appears with James Dixon, whom she described as her husband and whom some accounts call her lover. Dixon was the nephew of Ann Atkinson, a milliner from Kirkby Lonsdale in Westmorland who ran her own business with an assistant and three apprentices and came to London once a year to buy stock. Dixon drank, and he died. A bottle of colchicum was found in his room. The doctor who attended him wanted a post-mortem examination; Wilson begged him not to perform it, saying Dixon had a horror of being cut up, and he gave way. She had told that doctor Dixon was her brother, and told the Atkinson family he had died of consumption.
Maria Soames was a widow in her late forties who let the first floor of her London house to Wilson in 1855. Prosecutors said she, too, changed her will to benefit her lodger. She died on October 18, 1856, after an illness of violent pain. Wilson's explanation, then and afterward, was that Soames had poisoned herself in despair after a man named Taylor cheated her of money with a false promise of marriage. Taylor was himself on the list of people Wilson was later suspected of trying to poison; he survived.
The Soames trial opened at the Central Criminal Court on September 25, 1862, before Mr. Justice Byles, with Williams again for the defense. The prosecution wanted to show the jury that seven people Wilson had lived with as a nurse had died after altering their wills in her favor, almost all of them sufferers from gout; the judge refused to admit that evidence. The case therefore turned on Soames alone and on the toxicologist Alfred Swaine Taylor, who testified to colchicum poisoning. Williams answered that the drug could not be reliably detected in a body so long buried. In his summing-up Byles told the jury that "if such a state of things as this were allowed to exist no living person could sit down to a meal in safety." They convicted her, and he sentenced her to death.
It was the first death sentence the Central Criminal Court had passed on a woman in fourteen years, and a contemporary broadside noted that she was the first woman executed at Newgate since 1848. The Times observed that not a single effort was made on her behalf. She was hanged outside Newgate on October 20, 1862, before a crowd reported at twenty thousand in some accounts and twenty-five thousand in others, the last woman publicly hanged in London. She denied every charge to the end. After the trial Byles called Williams to his chambers, told him he had conducted the defense remarkably well but that the facts were too strong, and added that in his opinion Williams had that day defended "the greatest criminal that ever lived." The remark was made in private and became public through Williams's memoir.
Ann Atkinson's case was never tried; the indictment was not proceeded with once Wilson had been condemned. Byles had read the depositions in it, and said he had no more doubt that Mrs. Atkinson was murdered by Catherine Wilson than if he had seen the crime committed. Harper's Weekly, reporting the execution, went further and set out a list: Mawer and Dixon poisoned, a Mrs. Jackson robbed and poisoned, Soames and Atkinson murdered, an attempt on Taylor, the acid given to Carnell. It called the result "seven murders known, if not judicially proved," though its own list holds five deaths and two survivors. Only the death of Maria Soames was ever proved in a courtroom. Everything else rests on exhumations, on what the judge read, and on a newspaper's arithmetic.