The 31-year-old man at the wheel of a truck that plowed through Bastille Day revelers in this southern resort city was known to the police as a violent petty criminal who immigrated from Tunisia about 10 years ago.
But he was not known to have any links to terrorist groups, and neighbors said he did not seem interested in religion.
Many questions remain about Mohammed Lahouaiej Bouhlel, whose identity documents, cellphone and bank card were found inside the 19-ton commercial vehicle, and what might have motivated his murderous assault. Was he in touch with Islamist extremists? How did he procure the gun he fired at police before he was shot dead? Did he act independently or was he working with others?
The country has faced a number of horrific attacks by Islamist extremists, but as of late Friday, no group had claimed responsibility for Thursday's carnage in Nice.
Bouhlel was born in Tunisia and raised in Msaken, an affluent suburb of Sousse, where dozens of tourists were gunned down on a beach last year. He moved to France around 2005 and worked as a delivery-truck driver.
Like the perpetrators of previous assaults, Bouhlel had numerous brushes with the law, dating back to 2010, according to the Paris prosecutor, François Molins. But he was never flagged for signs of radicalization and was "completely unknown" to the country's intelligence services, Molins told reporters Friday.
He was accused of various crimes — including theft, vandalism and domestic violence — but had only one conviction in France. He received a six-month suspended sentence in March for assaulting a driver with a wooden pallet during an altercation following an accident, Justice Minister Jean-Jacques Urvoas said.
His lawyer at the time, Corentin Delobel, said his client did not appear to have psychological problems or to hold extremist views.
"He was quite normal in what he said, even in his physical appearance and his attire," Corentin Delobe told French TV.
There was nothing to indicate that he might be headed in this direction, Delobel said.
Although he was once married and had young children, Bouhlel's neighbors in a blue-collar area of Nice said he lived alone on the first floor of a modest five-story apartment block. He kept a small van parked nearby and was often seen carrying a bicycle into his apartment.
"I used to walk past him on the stairs sometimes," said Hiba, a French-born woman of Tunisian descent who, like others interviewed, did not want her full name published. "I didn't like the way he looked at me, it was … creepy. No manners either, always rude, and he pushed past everyone like he thought he was important."
At a nearby cafe, a grizzled man sipping from a glass of mint tea remembered seeing Bouhlel around the neighborhood.
"I notice everyone here. Everyone who comes, everyone who goes," said the man, who asked to be identified as Mr. Mehdi. "This man, he was not very popular. He never did anything bad to me, but he always had a bizarre attitude. And always alone. No friends! I heard he had a woman, but I never saw her. He always complained about her. Everyone knew this. A very bad man."
Bouhlel did not strike people as particularly religious. He was known to drink and smoke marijuana, did not attend mosque and often wore shorts.
"Clearly not a real Muslim," said Yassine Adam Hamza, an 18-year-old, as she was leaning on a bicycle.
"He was just a weird loner … I heard him shouting sometimes, I think maybe yesterday or the day before yesterday. See, he doesn't know how to behave."
A Tunisian man, who said he comes from the same village as Bouhlel, described to L'Express newspaper an ominous exchange the night of the attack.
"What happened Thursday night is that he drank with a colleague of his," said the man identified as Wissam. "They argued. His friend told him, 'You are worth nothing at all.' He answered him: 'One day, you will hear people talk about me!' "
Preliminary investigations did not suggest that he acted in the heat of the moment.
According to French news reports, Bouhlel rented the truck on Monday from a company in the nearby city of Saint-Laurent-du-Var, then parked it on Wednesday in Auriol, an eastern neighborhood of Nice.
Surveillance footage shows him returning to the neighborhood on a bicycle at around 9:30 p.m. Thursday. He enters the truck and drives west toward Promenade des Anglais.
At about 10:30 pm, he arrives in Magnan, a neighborhood just north of the famous palm-fringed boulevard, which was packed with people for a fireworks show.
Roughly 15 minutes later, he steers the truck into the crowd.
Zavis reported from Los Angeles. Special correspondent Harvey reported from Nice.
5 p.m.: This article was updated with comment from Bouhlel's former lawyer.