Styllou Christofi was born in Cyprus in 1900 and grew up in a small, isolated village without formal education. She married and had a son named Stavros. In 1925, she was arrested for the murder of her mother-in-law, allegedly by forcing a burning torch down the woman's throat. The outcome of this trial is unclear, with reports suggesting she was either acquitted or deemed to have been provoked.

In 1953, Christofi moved to London to live with her son Stavros, his German-born wife Hella, and their three children. Tensions arose between Christofi and Hella, particularly regarding the upbringing of the grandchildren. On the evening of July 29, 1954, after Stavros had left for work and the children were asleep, Christofi confronted Hella in the kitchen. She struck Hella on the back of the head with an ash pan, rendering her unconscious, then strangled her with a scarf. Attempting to dispose of the body, Christofi dragged Hella into the garden, poured paraffin over her, and set her on fire.

A neighbor, John Young, witnessed the fire but initially believed Christofi was burning a mannequin. Realizing the severity of the situation, Christofi sought help from passersby, leading to the arrival of the fire brigade and police. The authorities discovered Hella's body and evidence of the crime, including bloodstains and the removed wedding ring found in Christofi's room.

Christofi was arrested and charged with murder. During her trial at the Old Bailey, she claimed to have discovered the fire and attempted to extinguish it. The jury rejected her defense, and on October 28, 1954, she was found guilty and sentenced to death. Despite limited appeals for clemency, she was executed by hanging at Holloway Prison on December 15, 1954, becoming the penultimate woman executed in Britain before Ruth Ellis in 1955.