The 31-year-old Tunisian who killed 84 people by driving a truck through a Bastille Day crowd in Nice on Thursday spent years seeing psychologists before leaving Tunisia for France in 2005, his sister said.
As authorities in France frantically searched for clues that might indicate a network of supporters of the kind that emerged after the Paris attacks last November, what is known so far about Mohamed Lahouaiej Bouhlel suggests a troubled, angry loner who never responded to neighbors' greetings, suffered from depression and had little interest in Islam.
The Islamic State group's so called press agency claimed the Nice attack on Saturday, but it is unclear whether the man acted on his own initiative or as part of a plot.
Hollande, who has already extended a state of emergency by three months, is expected to assess all available options in response to the attack, which also injured more than 200 people, of whom 52 are critical. Where the cash came from is a mystery as Bouhlel has been unemployed for several months, leading to suspicions it could have come from an Islamic terrorist group.
"The individual who committed this absolutely despicable, unspeakable crime was not known by the intelligence services, as he had not stood out over the past years-whether through court convictions or through his activity-for support of radical Islamist ideology", Interior Minister Bernard Cazeneuve said.
Cazeneuve said the father-of-three "seemed to have been radicalized very quickly, from what his friends and family" have told police.
Today marks the first of three days of national mourning in France. In March, he was given a six-month suspended sentence by a Nice court for a road-rage incident.
Edwin Bakker, Professor at the Centre for Terrorism and Counterterrorism at the University of Leiden in the Netherlands, said the claim did not necessarily point to any formal link. "He gave cash to people he knew who were returning to our village and asked them to give it to the family".
People gather at a makeshift memorial to honor the victims of an attack on Friday, near the area where a truck mowed through revelers in Nice, France.
The group took approximately 36 hours to claim responsibility for the attack. Mohamed Mondher Lahouaiej-Bouhlel told French media from his Tunisian home: "He had some hard periods".
"I would like to take this opportunity to make a public statement to say that we share the grief of France in the rampage of multiple murders of their citizens", Mr. Duterte said in a statement.
Back in Tunisia, Bouhlel's father said his son was prone to violent episodes during which "he broke everything he found around him".