The French government Thursday announced a probe into security measures taken for the Bastille Day celebrations in Nice following accusations after the truck massacre that authorities had underestimated the jihadist threat.
A week after Mohamed Lahouaiej Bouhlel ploughed a 19-tonne truck into a crowd, killing 84 people, five suspects arrested over links to the Tunisian were to appear before anti-terrorism judges who will decide whether to charge them.
Lawmakers also adopted a law extending a state of emergency for six months, after it was toughened up by the right-dominated Senate.
The final version bans gatherings where sufficient security can not be provided and makes it easier to shut places of worship where preachers incite hate or violence.
While France mourns the victims of its third major terror attack in 18 months, the government continues to be plagued by questions over possible security failings.
Interior Minister Bernard Cazeneuve called for a police inquiry into the security measures taken in Nice, after an article in Liberation daily claiming that only one municipal police car was guarding the spot where Bouhlel crashed through barriers onto the promenade.
Cazeneuve has criticised the article as false and Prime Minister Manuel Valls has accused opponents who suggest the Nice attack could have been thwarted of "lying to the French".
The latest attack, which was claimed by the Islamic State group, has politicians tearing into each other, a far cry from the display of unity 18 months ago after the first strike against the Charlie Hebdo magazine and a Jewish supermarket.
Just hours after Valls warned that France must "learn to live with the threat", the group on Wednesday posted a video apparently shot in Iraq, showing two French-speaking jihadists threatening more attacks against the country.
However while IS claimed Bouhlel was one of its "soldiers", it has yet to publish footage or photos of the Tunisian as it did after previous attacks.
Investigators have said they have no proof yet that the driver, who was shot dead by police, had pledged allegiance to the group.
In Nice, investigators found a Kalashnikov rifle and a bag of ammunition in the basement of a 22-year-old man who is among five being held over links to Bouhlel.
The suspect received a text messages from Bouhlel on the night of the attack, in which Bouhlel praised him for providing the pistol he used during a shootout with police.
All five suspects -- four men and a woman -- are to appear before a judge Thursday to face possible charges.
About 100 investigators are poring over masses of data linked to the probe.
Pictures found on Bouhlel's cellphone indicate he was studying several locations where crowds gathered as possible targets.
One photo concerns a fireworks display on August 15, another a race on January 10 along the Promenade des Anglais where the attack took place, and another showed the opening times of the fan zone during the Euro football tournament.
Police interviewed hundreds of people close to Bouhlel, who said he had shown no interest in his Muslim religion until recently.
However about eight months ago he showed a friend a video of a hostage being decapitated, and shortly after that he snapped a picture of a news story about a car ramming a local cafe terrace.
His family and friends have described him as violent and possibly mentally disturbed.
Experts say his strategic planning and obsession with violence lean more towards psychopathy.
While unable to say whether Bouhlel suffered any mental illness at the same time, former FBI profiler Mary Ellen O'Toole said the majority of his reported traits were "only seen collectively in someone who is psychopathic."
"This is probably one of the most callous crimes you and I have ever heard of, it's very cold-blooded and it's predatory. He was actually hunting people to drive over."