Mohamed Salmene Lahouaiej-Bouhlel was born on January 3, 1985, in M'saken, Tunisia. This small town is located about 10 kilometers, or 6 miles, from the coastal city of Sousse. His upbringing was marked by family troubles, as his parents eventually divorced. His father remained in Tunisia and described his son as having faced significant challenges, including depression. According to him, Mohamed struggled with anger issues and exhibited violent behavior during his teenage years.

Lahouaiej-Bouhlel had a troubled personal life. He married a cousin who lived in France, and together they had three children. However, the marriage was rocky, with reports of domestic violence, leading to their separation. He had financial struggles and worked as a delivery truck driver. In 2005, he moved to Nice, France, where he eventually acquired a truck permit.

Lahouaiej-Bouhlel's life included activities such as training in martial arts and frequenting salsa nightclubs. He was reported to have a complicated sex life and had been involved in relationships with both men and women. Despite being in a marriage, he was known to have had an affair with a much older man.

Over the years, he sought help for his mental health issues. His family claimed that he had been seeing psychologists for several years. His father noted that from 2002 to 2004, Mohamed experienced problems that caused a nervous breakdown. In this time, he had episodes of anger and would often break things around him.

Before his last arrest in January 2016, Lahouaiej-Bouhlel faced legal issues, including being known to police for prior offenses involving violence. He had a suspended sentence for attacking a motorist and had fallen asleep at the wheel in a van, leading to his job loss.

In the months leading up to his death, Lahouaiej-Bouhlel began to show signs of increasing interest in religion. Reports indicated that he started attending a mosque shortly before the attack, although his family asserted that he had not been religious for most of his life. Checking online, he searched for religious texts and violent content related to extremist groups.

Mohamed Salmene Lahouaiej-Bouhlel carried out an attack in Nice, France, on July 14, 2016, during the Bastille Day celebrations. He drove a truck along the Promenade des Anglais, hitting a large crowd of people celebrating the holiday. The attack resulted in the deaths of 86 people and injured more than 400 others.

In the days leading up to the attack, Lahouaiej-Bouhlel had sent around €97,000 to his relatives in Tunisia. On July 12 and 13, he visited the attack site multiple times, taking selfies and surveying the area. Witnesses reported seeing him laughing among crowds just hours before the attack. On the night of the assault, he was approached by police officers trying to stop him, leading to Lahouaiej-Bouhlel being shot and killed.

His mobile phone was found in the truck after he was shot. Investigators discovered that he had researched the area and watched violent online content before the attack. There were reports suggesting that he had expressed support for jihadist groups and had become radicalized quickly in the weeks before his actions. There were differing views on his religious beliefs, with some describing him as not particularly religious at the time.

After the attack, an online agency linked to the Islamic State claimed that Lahouaiej-Bouhlel was one of their soldiers. They stated that the attack was a response to calls to target citizens from countries in the coalition fighting against the Islamic State. While a French prosecutor suggested that the attack showed signs of jihadist terrorism, a preliminary investigation did not link him to any established terrorist groups.