New York - US President Donald Trump on Thursday reiterated his call that the Uzbek immigrant accused of killing eight people when he drove a truck down a New York City bike path should get the death penalty.
The suspect, Sayfullo Saipov, told investigators he was inspired by watching Islamic State videos and began planning Tuesday's attack a year ago, according to a criminal complaint filed against him on Wednesday.
Saipov, 29, also said "he felt good about what he had done" and asked for permission to display the flag of the militant group Islamic State in his hospital room, the complaint said.
Trump on Wednesday had suggested sending Saipov to the Guantanamo Bay military prison in Cuba where multiple detainees are held, but on Thursday said that move would have been too complicated.
"Would love to send the NYC terrorist to Guantanamo but statistically that process takes much longer than going through the Federal system...," Trump said on Twitter on Thursday. In a subsequent Tweet, he added, "...There is also something appropriate about keeping him in the home of the horrible crime he committed. Should move fast. DEATH PENALTY!"
Saipov faces two charges, one of which carries the death penalty if the government chooses to seek it, Manhattan acting U.S. Attorney Joon Kim said.
The charges are one count of violence and destruction of motor vehicles causing the deaths of eight people and one count of providing material support and resources to a foreign terrorist organization - Islamic State, also known as ISIS.
The maximum penalty for the first is death; the maximum for the second life in prison, Kim said.
Dzhokhar Tsarnaev, the surviving member of a pair of ethnic Chechen brothers who killed three people and injured more than 260 when they bombed the 2013 Boston Marathon in an attack inspired by the al-Qaeda militant group, was sentenced to death in 2015. He is the only inmate among the 61 people on federal death row convicted for an act charged as terrorism.
Saipov's charging document said he waived his rights to remain silent, avoid self-incrimination and have an attorney present when he agreed to speak to investigators from his bed at Bellevue Hospital Center in Manhattan, where he was being treated after being shot by a police officer.
It said he was particularly motivated by a video where Abu Bakr al-Baghdadi - the leader of Islamic State - exhorted Muslims in the United States and elsewhere to support the group's cause.
Investigators found thousands of ISIS-related propaganda images and videos on Saipov's cellphone, the complaint said. Among them were video clips showing ISIS prisoners being beheaded, run over by a tank and shot in the face.
The Federal Bureau of Investigation said it had located another Uzbek man, Mukhammadzoir Kadirov, 32, wanted for questioning as a person of interest in the attack.
US law enforcement officials, speaking on condition of anonymity because the investigation was continuing, told Reuters that Saipov had been in contact with Kadirov and another person of interest in the investigation.
Tuesday's assault was the deadliest in New York City since the attack on September 11, 2001, when hijackers crashed two jetliners into the World Trade Centre, killing more than 2 600 people.
Five Argentine tourists, a Belgian, a New Yorker and a New Jersey man were killed in the attack.
Saipov, who lived in Paterson, New Jersey, allegedly used a pickup truck rented from a New Jersey Home Depot to run down pedestrians and cyclists along a 20-block stretch of the Manhattan bike path, before slamming into a school bus.
He got out of the truck brandishing what turned out to be a paint-ball gun and a pellet gun, authorities said, before a police officer shot him.
Seated in a wheelchair, Saipov appeared for a hearing in Manhattan federal court on Wednesday before Magistrate Judge Barbara Moses. Public defense attorney David Patton was appointed to represent him.
Saipov did not ask for bail and was remanded to federal custody. It was not immediately clear where he would be held.
Earlier on Wednesday, Trump called him "this animal" and lambasted the U.S. justice system for terrorism suspects as "a joke" and "a laughingstock".