Mohamed Lahouaiej-Bouhlel, a 31-year-old Tunisian, was known to law enforcement for petty theft and domestic violence.
French authorities and media have yet to produce any evidence that the killer, Mohamed Lahouaiej Bouhlel, was radicalized.
French Interior Minister Bernard Cazeneuve, asked yesterday if he could confirm the attacker's motives were linked to jihadism, said: "No".
Rachel Maddow gives her take on the Bastille Day tragedy in France, the USA presidential candidates' responses to the attack and Donald Trump's running mate Mike Pence.
France is observing three days of national mourning in homage to the victims - although that hasn't stopped politicians from sniping at each other over who bore responsibility for the failing to stop the attack.
At least 10 children and teenagers were among the dead as well as tourists from the United States, Russia, Ukraine, Switzerland and Germany. "I took him to a psychiatrist, he took his treatments and he said he had a serious illness". A French parliamentary inquiry last week criticized numerous failings by the intelligence services over the Paris attacks.
France has been under a state of emergency ever since the November 13 Paris attacks, which came after 17 were killed in another attack in January at various sites including the Charlie Hebdo magazine and a Jewish supermarket.
Stephanie Simpson, from the Lenval children's hospital in Nice, said five children remained in critical condition, one was in a "very bad" condition, three were on artificial respiration, one had been stabilised and one eight-year-old child remained unidentified.
The attacker was supposed to return the truck on Wednesday, more than 24 hours before he drove it through the crowd which had gathered for Bastille Day.
Police and members of the public risked their own lives trying to stop the lorry as it travelled for more than a mile along the Promenade des Anglais as people headed home from a fireworks display to mark the French national holiday.
"My wife is dead, where is my son?"
"What I know is that he didn't pray, he didn't go to the mosque, he had no ties to religion", said the father, noting that Bouhlel didn't respect the Islamic fasting rituals during the month of Ramadan.
France, which has a Muslim population of almost five million, is also home to hundreds of jihadists who have flocked to fight alongside IS. The driver made it two kilometres along the promenade before being shot and killed by police in front of the Casino du Palais de la méditerranée.
- A man attacks soldiers protecting a Jewish community center in Nice.
"From 2002 to 2004, he had problems that caused a nervous breakdown", the father reportedly said.
"There is one minor (at Lenval) who could be the missing child", it added.