(CNN)The man accused of using a truck to plow down pedestrians and cyclists on a New York bike path and killing eight people was so devoted to ISIS that he wanted to display the terror group’s flag in his hospital room, documents show.
Sayfullo Saipov, a 29-year-old Uzbek native, did not say much when he made his initial court appearance Wednesday using a wheelchair.
But according to a criminal complaint, Saipov waived his right to silence and told investigators that he had planned Tuesday’s attack for about a year. He was inspired and motivated to carry out the attack after watching ISIS videos and closely followed the ISIS playbook for an attack, according to the complaint.
Saipov had about 90 videos and 3,800 images on his cell phone featuring ISIS propaganda, including video of a beheading, according to the complaint.
The details that emerged Wednesday paint a picture of a man who reportedly planned more carnage after the attack on the Lower Manhattan bike path near the World Trade Center. Police shot Saipov after he crashed into a school bus and left the truck brandishing imitation firearms, officials said.
He picked Halloween to carry out the deadliest attack in New York since 9/11 because he believed more people would be out on the streets for the holiday, according to the criminal complaint. More than a dozen people were also injured Tuesday.
Saipov is charged with providing material support to ISIS, violence and destruction of motor vehicles, said Joon H. Kim, acting US attorney for the Southern District of New York.
Saipov didn’t enter a plea Wednesday to the federal terror charges, a source at the US attorney’s office told CNN.
Trump tweets about death penalty
On Twitter, President Donald Trump said Saipov should be executed and added that he “would love” to send him to the Guantanamo Bay detention camp in Cuba.
“NYC terrorist was happy as he asked to hang ISIS flag in his hospital room. He killed 8 people, badly injured 12. SHOULD GET DEATH PENALTY!’ the President tweeted Wednesday night.
In prepared remarks Thursday, US Attorney General Jeff Sessions did not rule out using Guantanamo Bay to prosecute terrorists. The remarks did not specifically refer to the Saipov case.
“Terrorists should know: This administration will use all lawful tools at our disposal, including prosecution in Article III courts and at Guantanamo Bay,” Sessions said.
After his arrest, Saipov told investigators who talked to him at Bellevue Hospital that he planned the attack for about a year. Two months ago, he said, he decided to use a truck “to inflict maximum damage against civilians,” the complaint said.
On October 22, he rented a truck from a Passaic, New Jersey, store that authorities earlier had identified as Home Depot to practice making turns ahead of the attack, according to the complaint.
On Tuesday, he went to the same store and rented the truck for two hours. He “had no intention of ever returning it,” the complaint said.
He planned to use the truck to hit pedestrians in the area where he carried out the attack and “then proceed to the Brooklyn Bridge to continue to strike pedestrians,” it said.
“Saipov wanted to kill as many people as he could,” the complaint said.
Investigators also sought to question Mukhammadzoir Kadirov, 32, an Uzbek national, in relation to the attack. Law enforcement sources said Wednesday night they found the man and are questioning him.
“We have found him, and we’ll leave it at that,” said William Sweeney, assistant director in charge of the FBI’s New York field office.
Authorities did not find any flags near the truck, but they found a handwritten note in Arabic expressing affinity for ISIS.
“The gist of the note was the Islamic State would endure forever,” said John Miller, deputy commissioner for intelligence and counterterrorism for the New York police.
ISIS has not made any claim of responsibility for the attack, but Saipov told investigators that the group’s videos inspired him, in particular one that shows ISIS leader Abu Bakr al-Baghdadi questioning “what Muslims in the United States and elsewhere were doing to respond to the killing of Muslims in Iraq,” the complaint said.
The videos that law enforcement found on Saipov’s cell phone include graphic scenes of ISIS fighters killing prisoners, beheadings and “instructions for how to make a homemade improvised explosive device,” the complaint said.
Saipov has also been linked to social media accounts that contain ISIS-related material, a law enforcement official said.
The tactic of turning an ordinary vehicle into a lethal weapon is familiar to groups such as ISIS. In 2014, an ISIS spokesman called for attacks using improvised weapons such as knives, rocks, poison and cars.