New Orleans attacker Shamsud-Din Jabbar recorded a video of the city's French Quarter using Meta glasses he wore while cycling in the weeks before his deadly atrocity, the FBI has said.
The bureau said he had made two trips to the southern US city in October and November this year.
The US citizen, from Houston, Texas, killed 14 people when he rammed his rental truck into a crowd celebrating New Year in Bourbon Street in the French Quarter early on 1 January.
The 42-year-old former US army soldier was then killed in a shootout with police at the scene of the deadly crash.
The FBI said the first trip, where he stayed at a rental home, started on 30 October, and lasted at least two days, and he was also there on 10 November.
It said he made the cycling video on his first visit using the hands-free glasses, which were developed by US tech giant Meta and are capable of recording or livestreaming. They are designed to look like normal glasses and come in a range of styles.
What happened in the hours before the attack?
The agency said Jabbar entered Louisiana around 2.30pm on 31 December - hours before the terror attack.
It said he placed one IED (improvised explosive device) in the area of the atrocity at 1.53am on New Year's Day and a second one was placed soon after at 2.20am.
At 3.15am, Jabbar carried out his attack, where he "used the truck as a lethal weapon", said the FBI.
Shortly after 5am, a fire was reported at a rental home in New Orleans, where emergency services found explosive devices.
The FBI believes Jabbar acted alone.
"We have not seen any indications of an accomplice in the United States, but we are still looking into potential associates in the US and outside of our borders," Deputy Assistant Director Christopher Raia said at a news conference.
Jabbar also travelled to Cairo, Egypt, between 22 June and 3 July 2023, and a few days later on 10 July he flew to Ontario, Canada, before returning to the US on 13 July.
But it was not yet clear whether those trips were connected to the truck attack.
"Our agents are getting answers to where he went, who he went with and how those trips may or may not tie into his actions here," said Lyonel Myrthil, FBI special agent in charge of the New Orleans Field Office.
Jabbar proclaimed his support for the so-called Islamic State militant group in online videos posted hours before he struck.
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