Christine Papin was born on March 8, 1905, in Le Mans, France. Her mother, Clémence, was seen as unfit for motherhood. Because of this, shortly after Christine was born, she was given to her paternal aunt and uncle to raise her. Christine lived with them for seven happy years.

Christine had a younger sister named Léa, born on September 15, 1911. After their mother Clémence and father Gustave divorced in 1913, Léa was sent to live with her maternal uncle until he passed away. During this time, there were troubling events in the family. Their older sister, Émilia, faced a traumatic incident and was later sent to the Bon Pasteur Catholic Orphanage. Soon after, both Christine and Léa were sent to the same orphanage by their mother. Clémence hoped the sisters would stay there until they turned fifteen when they could start working.

At the orphanage, Christine showed the desire to become a nun, but her mother did not support this wish. Instead, she placed Christine in various jobs, training her in household duties, which set the stage for her future work as a live-in maid. Christine was known as a hard worker and a good cook. However, she could also be insubordinate at times. Léa was described as quiet and obedient, but it was believed that she was not as intelligent as Christine.

The sisters often worked together as maids in different homes around Le Mans. They preferred to remain together, helping each other through the challenges of their jobs. Their employers appreciated their work, but Clémence was not satisfied with the pay they received. She often pressured them to seek better opportunities.

On the evening of February 2, 1933, Christine and Léa Papin were at the house of the Lancelin family in Le Mans. Madame Léonie Lancelin and her daughter Genevieve returned home after shopping to find the lights off. The Papin sisters explained that a power outage occurred because Christine had plugged in a faulty iron. This upset Madame Lancelin, and she began to physically attack the sisters on the first-floor landing.

In the heat of the moment, Christine attacked Genevieve and gouged her eyes out. Léa followed Christine's lead and attacked Madame Lancelin, also gouging her eyes out. After the initial attacks, Christine went to the kitchen, where she took a knife and a hammer. She brought these weapons back upstairs, and the attack continued. The sisters struck the Lancelin women multiple times, causing severe injuries, including mutilation.

Later that evening, Monsieur Lancelin returned home and found the house dark. Assuming his wife and daughter went to a dinner party, he left for the event but soon realized they were missing. He returned home with his son-in-law to find the front door bolted from the inside. Feeling suspicious, they went to a local police station for help.

When the police arrived, an officer climbed over the garden wall to get inside. He discovered the bodies of Madame Lancelin and Genevieve. They were brutally beaten and unrecognizable. Madame Lancelin’s eyes were found in the folds of her scarf, while one of Genevieve’s eyes was found under her body, and another was located on a staircase.

After searching for the Papin sisters, the officer found their door locked upstairs. Losing no time, he called a locksmith to open the door. Inside, he found Christine and Léa naked in bed, and nearby was a bloody hammer with hair still attached.

Under questioning, the sisters confessed to the murders right away. They claimed it was in self-defense. During their trial, they continued to protect each other while each took sole responsibility for the events of that night. They were eventually separated in prison, which deeply affected Christine. She became distressed and, at one point, even attempted to harm herself.

The trial revealed inconsistencies in their mental health assessments. While the court ultimately deemed them sane, they were diagnosed with Shared Paranoid Disorder. The jurors took only 40 minutes to declare them guilty. Christine was sentenced to death, but this was later changed to life imprisonment. Léa received a 10-year sentence.

Christine struggled in prison, especially after being separated from Léa. She suffered from severe depression and refused to eat, which led to her death on May 18, 1937. Léa served eight years of her sentence and, upon release, lived under a false identity. Reports about her later life differ, with some stating she died in 1982 and others claiming she passed away in a hospice in 2001. The sisters are buried together in a cemetery in Nantes.