The investigation into the New York City terror attack that killed eight people Tuesday led authorities to additional people of interest and now, terrorism charges. 

On Wednesday, the FBI released a poster saying it was looking for one of suspect Sayfullo Saipov’s associates, former Tampa resident Mukhammadzoir Kadirov, only to announce less than 90 minutes later that it had found him. 

A law enforcement official said Kadirov was a friend of Saipov’s and may not have any role in the case. The official wasn’t authorized to speak publicly and spoke only on condition of anonymity.

Investigators in multiple states raced to retrace Saipov’s steps and understand his motivations, which they said were illuminated by a note he left by the truck: “Islamic Supplication. It will endure.” The phrase “it will endure” commonly refers to the Islamic State group, and Saipov had a cellphone loaded with the group’s propaganda, an FBI agent said in the criminal complaint.

Meanwhile, Saipov was charged Wednesday with one count of providing material support and resources to a terrorist organization, and one count of violence and destruction of motor vehicles.

Prosecutors say Saipov rented a truck from Home Depot and drove it for blocks down a crowded Manhattan bike path, killing eight people. 

A married father and former commercial truck and ride-hailing driver, Saipov began planning an attack a year ago and settled on a truck assault a couple of months ago, according to the criminal complaint.

Saipov allegedly told investigators he planned on killing more people in the name of ISIS. 

Investigators also said Saipov "felt good about what he had done" and that he wanted to fly the ISIS flag in his hospital room. 

The White House is calling Saipov an enemy combatant, and President Donald Trump said he was considering sending Saipov to Guantanamo Bay — although that move would be unprecedented. 

Detainees at Guantanamo accused of supporting militants have faced military tribunals, rather than trials in the U.S. legal system.

Late Wednesday night, the president took to Twitter to say that Saipov should get the death penalty. Trump also has called for eliminating the 1990s visa lottery program that Saipov used to come to the U.S. in 2010.

John Miller, deputy New York police commissioner for counterterrorism, said Saipov had never been the subject of a criminal investigation by the FBI or New York police, but appears to have links to people who have been investigated. He wouldn’t elaborate.

The attack killed five people from Argentina, one from Belgium and two Americans, authorities said. Twelve people were injured.

Handcuffed and with his legs shackled in court Wednesday, Saipov nodded his head as he was read his rights in a brief court proceeding that he followed through a Russian interpreter. Outside court, his appointed lawyer, David Patton, said he hoped “everyone lets the judicial process play out.”

“I promise you," Patton said. "That how we treat Mr. Saipov in this judicial process will say a lot more about us than it will say about him."

Information from the Associated Press was used in this story.