He was a divorcee, a drunkard and a delivery man. On Thursday, he murdered 84 people as they watched the fireworks on Nice's Promenade des Anglais.
Mohamed Lahouaiej-Bouhlel didn't pray, didn't fast, drank alcohol and used drugs, his father revealed on Saturday.
From his 12th floor cramped and shabby flat in Nice, Lahouaiej-Bouhlel plotted to turn a 19-tonne refrigerator truck into a tank.
On Bastille Day, that tank would take 10 children and many more parents with it as it veered violently from left to right down more than two kilometres of the seaside promenade.
In its path was 27-year-old Parisian Timothy Fournier, who died in efforts to save his pregnant wife, and 11-year-old junior baseballer, Brodie Copeland, who was run down with his father Sean, along with hundreds of other men, women and children including 21-year-old Russian student, Victoria Savchenko.
Those neighbours who knew Lahouaiej-Bouhlel at the apartments in Nice's Quartier des Abattoirs told The New York Times he tended to grunt to "bonjour" and beat his wife.
Lahouaiej-Bouhlel had only ever had one conviction before, for road rage, despite being known to police for violence and petty theft.
Born in 1985 in Tunisia, Lahouaiej-Bouhlel was not known by Tunisian authorities to hold extremist views, and while he held a French resident permit for the past 10 years, he never obtained nationality, according to Al Jazeera.
To French authorities, Lahouaiej-Bouhlel had remained under the radar, a miscreant but no martyr.
His father, Mohamed Mondher Lahouaiej-Bouhlel told Agence France-Presse that his son had battled with depression.
"From 2002 to 2004, he had problems that caused a nervous breakdown. He would become angry and he shouted … he would break anything he saw in front of him," said Lahouaiej-Bouhlel.
"He didn't pray, he didn't fast, he drank alcohol and even used drugs," he said.
A neighbour who asked only to be identified as Jasmine told The Guardian UK: "He was quite handsome, greyish hair, looked a bit like George Clooney."
"He never answered when we spoke or said hello, he just sort of stared at us aggressively."
"I was really scared of him. All I knew is that he had trouble with his wife, but we never saw her or their kids. He spent a lot of his time at a bar down the street where he gambled and drank."
It remains unclear what drove Lahouaiej-Bouhlel to pile a truck with ammunition, grenades and guns and run down those families who spilled out from the cafes and restaurants on one of France's most famous promenades to watch the fireworks.
The 31-year-old's modus operandi appears to come straight out of the Islamic State textbook.
Just last month ISIS's Cyber Caliphate channel promoted using cars for terrorism after its spokesman Abu Muhammad al-Adnani urged followers to murder non-believers "with a rock, or slaughter him with a knife, or run him over with your car, or throw him down from a high place, or choke him, or poison him."
But neighbours' recollections of Lahouaiej-Bouhlel don't point to a man of religious fervour – he often dressed in shorts, enjoyed salsa music and was not known to the mosques in Nice.
Tellingly, ISIS, waited until Saturday night to claim responsibility for the terrorist attack.
