Geneviève Lhermitte was born on November 16, 1966, in Brussels, Belgium. Her parents were Michel Lhermitte, a businessman and student, and Marina Schoevaert, a nurse. She was the oldest of three sisters, with her younger sisters being Catherine, born in 1969, and Mireille, born in 1972.

During her time in secondary school, Lhermitte faced challenges with her studies and had low self-confidence. Despite these struggles, she graduated in 1991 with a diploma in French and History from the Educational Institute of Social Promotion of the French Community in Uccle. While attending this school, she met Bouchaib Moqadem, who was studying mathematics and physics.

Lhermitte and Moqadem got married on September 22, 1990. After their marriage, they moved into the apartment of Michel Schaar, a physician who had known Moqadem's family for years. Schaar provided financial support for the family, allowing Moqadem to work at a convenience store while Lhermitte began her teaching career in 1991.

Shortly after starting her job as a teacher, Lhermitte became a mother. She gave birth to her first daughter, Yasmine, on August 13, 1992. Lhermitte had another daughter, Nora, on February 13, 1995. She took a leave of absence from her teaching job due to postpartum depression from June 1, 1995, to August 31, 1996. During this time, Schaar bought a house for his family to live in, while he remained the primary financial provider.

In addition to Yasmine and Nora, Lhermitte later had two more daughters, Miriam, born on April 20, 1997, and Mina, born on May 20, 1999. The family moved to Nivelles in Belgium, where they lived in the home Schaar had purchased. Moqadem began working as Schaar's filing assistant part-time in 1996 and started full-time in 1998.

As time passed, tensions grew between Lhermitte and her husband. Moqadem often spent long hours out of the house and traveled frequently to Morocco to visit his family. On August 9, 2003, Lhermitte gave birth to her only son, Mehdi. In 2006, Schaar suggested that Lhermitte see a psychiatrist due to her mental health. She began consulting with psychiatrist Diderick Veldekens in 2005.

On 28 February 2007, Geneviève Lhermitte killed her five children in their home in Nivelles, Belgium. Her husband was away visiting family in Morocco at the time. Lhermitte took her oldest daughter, Yasmin, to a dermatology appointment. After picking up her other children from school, she prepared lunch for them. Later, she heard a voice saying, "the machine is running."

Before the murders, Lhermitte mailed letters to her sisters and a friend. In her letter to her friend, she expressed anger towards her husband and another man, Michel Schaar, who had been a significant presence in their lives. After sending these letters, she took two knives from a grocery store and hid them in a drawer at home.

Lhermitte first attacked her youngest daughter, Mina. She attempted to strangle her but, when Mina fought back, Lhermitte sliced her throat with one of the knives while apologizing. Next, she killed her only son, Mehdi, in a similar fashion after failing to strangle him.

Lhermitte then called her daughter Myriam into the office with a promise of a surprise. Once Myriam entered, Lhermitte hit her on the head with a marble plaque and cut her throat. The fourth child, Nora, was also killed in the same manner when Lhermitte asked her to sit down and then attacked her from behind.

Finally, Lhermitte attacked her oldest daughter, Yasmin, as she entered the office. Although Yasmin initially tried to evade her mother, she was ultimately overpowered and suffered fatal injuries.

After the murders, Lhermitte attempted to end her own life but failed. Realizing she was still alive, she wrote "call the police" on her door before contacting emergency services. When investigators arrived, they found all five children in their beds, some holding stuffed toys.

Lhermitte confessed to the murders during her trial, which began on 8 December 2008. It lasted two weeks, focusing on her mental state. Despite arguments from psychiatrists that she was not of sound mind and should be in a psychiatric facility, the jury sentenced her to life in prison without considering any extenuating circumstances.

In the years following her conviction, Lhermitte filed lawsuits, including one against her psychiatrist claiming negligence contributed to the tragedy. In 2019, she was transferred to a psychiatric prison. On 28 February 2023, the sixteenth anniversary of the murders, Lhermitte was euthanized at the age of 56.