Ada Chard Williams was born around 1875 in England. Details about her early life remain scarce, but by the late 19th century, she had married William Chard Williams and became involved in "baby farming," a practice where individuals took in infants for a fee, often under the pretense of adoption or childcare. Operating under the alias "Mrs. Hewetson," Ada placed advertisements in local newspapers offering to find homes for unwanted children, a service that, while common at the time, was rife with neglect and abuse.

In September 1899, Florence Jones, a young unmarried mother, responded to one of Ada's advertisements. She arranged to pay £5 for the adoption of her 21-month-old daughter, Selina Ellen Jones, but could only provide £3 upfront. When Florence returned with the remaining £2, both Ada and Selina had vanished. Concerned, Florence reported the incident to the police. ​

On December 5, 1899, Ada wrote to the Criminal Investigation Department, admitting to being a baby farmer but denying any involvement in Selina's disappearance. She claimed to have passed the child to a "Mrs. Smith" in Croydon. However, this assertion was undermined when Selina's body was discovered on the banks of the Thames at Battersea. The child had been bludgeoned and strangled, her body tied with a distinctive "fisherman's bend" knot—a method linked to other suspicious child deaths.

Ada and her husband were arrested and stood trial at the Old Bailey on February 16 and 17, 1900. While Ada was found guilty and sentenced to death, her husband was acquitted, though the jury believed he was an accessory after the fact. Ada Chard Williams was executed by hanging at Newgate Prison on March 6, 1900, becoming the last woman to be executed there. She was suspected of involvement in other child deaths, but no further charges were brought against her.