Mohamed Lahouaiej-Bouhlel had grown a beard in the eight days before he carried out the attack and told friends the significance of the beard is religious, prosecutor François Molins told a press conference.
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Investigators had found no proof of any allegiance or any direct link to Islamic State or other terrorist organisations, according to Molins. However, Lahouaiej-Boulels computer contained very violent images from radical Islamic sites and links to jihadi websites, as well as articles about the Bastille Day fireworks display in Nice, the recent nightclub attack in Orlando, shootings in Dallas, the killing of two police officers in Paris suburb Magnanville, and research into Osama bin Laden and the Algerian terrorist leader Mokhtar Belmokhtar.
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On 7 July, Lahouaiej-Bouhlel had researched the Quran on his computer as well as religious songs.
He picked up the lorry used to carry out the massacre on 8 July at 8.30am. He was due to return it on 11 July and left a guarantee cheque for 1,600. In the three days before the attack he went to the Promenade des Anglais several times.
https://www.theguardian.com/world/2016/jul/18/nice-attack-premeditated-mohamed-lahouaiej-bouhlel-beard-prosecutor