Elizabeth Martha Clark was born around 1811 in Dorset, England, to John and Martha Clark. She first married Bernard Bearn at the age of 20, and the couple had two sons, William and Thomas, both of whom died young. After approximately a decade of marriage, Bernard passed away. Elizabeth later worked as a housekeeper, where she met John Brown, a man nearly 20 years her junior. They married in 1852 and resided in Birdsmoorgate, near Beaminster, Dorset.

On 5 July 1856, following a heated argument during which John Brown allegedly returned home intoxicated and physically assaulted Elizabeth, she retaliated by striking him multiple times with an axe, leading to his death. Initially, Elizabeth claimed that John had been kicked by a horse, but inconsistencies in her account led to her arrest. She was tried and found guilty of murder in August 1856. Her execution took place on 9 August 1856 outside Dorchester Prison, witnessed by a crowd that included the young Thomas Hardy, who was profoundly affected by the event and later drew inspiration from it for his novel "Tess of the d'Urbervilles."​