A US Army veteran who killed 14 people by ramming a truck into New Year's Day revellers in New Orleans had pledged allegiance to Islamic State and appeared to have made recordings in which he condemned music, drugs and alcohol.
Shamsud-Din Jabbar, a 42-year-old Texas native who once served in Afghanistan, acted alone in the attack, the FBI said on Thursday, reversing an earlier assessment that he might have had accomplices.
He was killed in a shootout with police after the rampage, which also injured dozens of people and has been labelled by the FBI as an act of terrorism.
"It was premeditated and an evil act," FBI Deputy Assistant Director Christopher Raia told a news conference on Thursday, reaffirming the bureau's conclusion that Jabbar was inspired by Islamic State, the militant group with fighters in Iraq and Syria.
Raia said investigators were looking into Jabbar's "path to radicalisation" from military veteran, real estate agent and one-time employee of consulting firm Deloitte into someone who was "100 per cent inspired by ISIS", or Islamic state.
An Islamic State flag flew from a staff attached to the back of the rented truck used in the attack.
Though greatly weakened by a sustained military campaign by a US-led coalition, Islamic State has continued to recruit sympathisers online, experts say.
Jabbar's half-brother was also searching for answers, saying Shamsud-Din Jabbar had been struggling to get past a recent divorce but he showed no signs of anger just weeks before the attack.
"He was smart, funny, charismatic, loving, compassionate, humble and literally wouldn't hurt a fly," Abdur Rahim Jabbar told Reuters at his home in Beaumont, Texas.
"That's why it's so devastating. This degree of maliciousness is not like him. We are trying to understand what changed, too."
The massacre on New Orleans' famed Bourbon Street in the French Quarter during a holiday celebration and an explosion outside the Trump International Hotel in Las Vegas have made for an unnerving start to 2025 in the US.
The FBI said it had found no definitive link between the New Orleans attack and the Cybertruck explosion in Las Vegas later on the same day, which killed the driver and left seven people with minor injuries.
Law enforcement officials across the country are promising heightened security for public events.
The Sugar Bowl college football game that had been scheduled for Wednesday in New Orleans was rescheduled for Thursday under increased security and with a moment of silence to honour the victims.
Bourbon Street reopened to the public amid heightended security earlier in the day.
The city is also readying for weeks of Mardi Gras celebrations that begin on January 6 and will host the National Football League's Super Bowl in February, with city officials promising heightened security for the crowded events.
Shamsud-Din Jabbar had recently renewed his Muslim faith after abandoning it in his 20s and 30s, his half-brother said.
He appeared to have made a series of religious audio recordings 11 months ago on SoundCloud that contained views on the evils of music as well as condemning drugs and alcohol.
"Music is the voice of Satan. ... Satan's voice is also the misleading of people from Allah's way," Shamsud-Din Jabbar says in one of the recordings.
He also decries the use of "intoxicants like marijuana, alcohol, sedatives, opioids, stimulants".
Jabbar had faced family and financial struggles, including helping to arrange care for his father following a stroke in 2023, and his divorce in 2022 from his second wife, with whom he fathered a child.
According to the FBI, Jabbar drove from Houston to New Orleans on December 31.
On the morning of the attack, he posted five videos on Facebook in which he said he had joined Islamic State in 2024 and provied his last will and testament, the FBI said.
Surveillance video showed Jabbar placing two improvised explosive devices in coolers a few hours before the attack at intersections around Bourbon Street, but both were rendered safe at the scene.
