A laptop, mobile phone and watch are still under review nearly a week after 37-year-old Matthew Livelsberger fatally shot himself just before the truck blew up.
A review of Livelsberger's searches through ChatGPT indicate he was looking for information on explosive targets, the speed at which certain rounds of ammunition would travel and whether fireworks were legal in Arizona.
Kevin McMahill, sheriff of the Las Vegas Metropolitan Police Department, called the use of generative AI a "game-changer" and said the department was sharing information with other law enforcement agencies.
"This is the first incident that I'm aware of on US soil where ChatGPT is utilised to help an individual build a particular device," he said.
"It's a concerning moment."
Sheriff Kevin McMahill says the use of generative AI in the attack is a worry for police. (AP PHOTO)
During a news conference, Las Vegas police and federal law enforcement officials unveiled new details about the New Year's Day explosion.
Among the details law enforcement disclosed: Livelsberger stopped during the drive to Las Vegas to pour racing-grade fuel into the Cybertruck.
The vehicle was loaded with 27 kilograms of pyrotechnic material and officials are still uncertain exactly what detonated the explosion, but said it could have been the flash from the firearm that Livelsberger used to fatally shoot himself.
Livelsberger, an Army Green Beret who deployed twice to Afghanistan and lived in Colorado, left notes saying the explosion was a stunt meant to be a "wake up call " for the nation's troubles, officials said last week.Â
He left phone notes saying he needed to "cleanse" his mind "of the brothers I've lost and relieve myself of the burden of the lives I took."
The explosion caused minor injuries to seven people but virtually no damage to the Trump International Hotel. Authorities said Livelsberger acted alone.
Livelsberger's letters touched on political grievances, societal problems and domestic and international issues, including the war in Ukraine.
He wrote that the US was "terminally ill and headed toward collapse".
Investigators had been trying to determine if Livelsberger wanted to make a political point, given the Tesla and the hotel bearing the president-elect's name.
Livelsberger harboured no ill will toward President-elect Donald Trump, law enforcement officials said. In one of the notes he left, he said the country needed to "rally around" him and Tesla CEO Elon Musk.
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