Carl Girouard was born around 1996 and grew up in Sainte-Thérèse, a suburb on Montreal’s North Shore in Quebec, Canada. Limited details are publicly available about his childhood or family life, but he was known to have struggled with mental health issues prior to his crimes. At age 19, five years before the attack, Girouard had expressed disturbing thoughts to a doctor, including threats to commit acts of mass violence. 

On the night of 31 October 2020, during Halloween celebrations, Carl Girouard carried out a deadly rampage in Quebec City. Dressed in a medieval costume and wielding a katana-style saber, he targeted unsuspecting pedestrians near the National Assembly of Quebec.

The attack began around 10:30 p.m. in the Old Quebec neighborhood, a popular area filled with historic streets and nightlife. Over the course of the assault, Girouard stabbed multiple victims chosen at random.

Two people were killed:

• François Duchesne, 56, communications director at the Musée national des beaux-arts du Québec
• Suzanne Clermont, 61, a hairdresser and beloved mother of two

Five other individuals were seriously injured but survived. Witnesses described a scene of chaos as Girouard roamed the streets in costume, ambushing victims without warning.

Girouard had brought gasoline containers in his car, suggesting he intended further destruction. Police later stated that he was prepared to inflict mass casualties, though he was ultimately stopped before escalating the attack further.

He was arrested by police shortly after the killings without being shot, and investigators quickly determined that his motives were not tied to terrorism. Instead, they traced his actions back to long-standing mental health struggles and violent ideation.

On 18 June 2021, prosecutor François Godin filed a direct indictment against Girouard, sending the case straight to trial without a preliminary hearing. After a trial in May 2022, the jury deliberated for five days before finding Girouard guilty of two counts of first-degree murder and five counts of attempted murder on 20 May 2022.

On 10 June 2022, he was sentenced to life imprisonment, with the possibility of parole after 25 years, the mandatory minimum under Canadian law for first-degree murder.