Born in 1933 in Overmere, Belgium, Cecile Bombeek entered the Apostolic Congregation of St. Joseph in Wetteren at the age of 24, adopting the name Sister Godfrida. She dedicated herself to religious life and nursing, eventually becoming the head nurse of the geriatric ward, known as "the Chronic," at a public hospital in Wetteren. Her colleagues regarded her as a devout and diligent caregiver. In 1974, Sister Godfrida underwent surgery to remove a malignant brain tumor. Post-surgery, she suffered from severe headaches and was prescribed potent painkillers, leading to a morphine addiction. Her behavior changed markedly; she began stealing drugs, falsifying prescriptions, and engaging in inappropriate relationships with both fellow nuns and a retired missionary priest. Additionally, she developed a penchant for luxury, frequenting fancy restaurants and purchasing provocative clothing.

Between 1976 and 1977, the geriatric ward under Sister Godfrida's supervision experienced an unusually high mortality rate, with 21 deaths in 1977 compared to the annual average of 13. Staff members grew suspicious of the increasing deaths and Sister Godfrida's erratic behavior. They documented incidents of patient mistreatment and unexplained fatalities, eventually reporting their concerns to hospital authorities, who initially dismissed them. 

On February 10, 1978, Sister Godfrida was arrested on charges of forgery related to her drug thefts. During interrogation, she confessed to murdering three elderly patients—Leon Matthys (81), Irma De Backer (79), and Maria Vanderginst (87)—by administering lethal insulin overdoses, claiming they were "too difficult at night." She insisted that she acted "sweetly" and that none of the victims suffered. Authorities suspected she might have been responsible for up to 30 deaths, but only three were confirmed. 

The case attracted international media attention, with sensational stories about the "killer nun" appearing in publications like Time magazine. Sister Godfrida was committed to a psychiatric institution, where she remained until her death in 2019 at the age of 86.

The notoriety of her crimes inspired the 1979 Italian film Killer Nun (Suor Omicidi), starring Anita Ekberg as a morphine-addicted nun who commits a series of murders in a hospital. ​