(CNN) New York terror suspect Sayfullo Saipov faces federal terrorism charges in connection with Tuesday's truck attack in Manhattan.
Saipov was charged with providing material support to ISIS and violence and destruction of motor vehicles. A criminal complaint filed Wednesday in New York's Southern District Court lays out evidence collected so far in support of the charges.
After his arrest, Saipov spoke to investigators at Bellevue Hospital, the complaint states. Here are some highlights from his interview and the investigation.
Saipov told investigators that about two months before the attack, he decided to use a truck "to inflict maximum damage against civilians," the complaint states.
Saipov told investigators he watched ISIS videos on his cellphone that inspired the truck attack, the complaint states. Investigators searched two cellphones and found about 90 videos and 3,800 pictures, many of which were ISIS-related propaganda.
In particular, Saipov said he was motivated to proceed after watching a video of 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 second cellphone's Internet history shows searches for a truck rental store in New Jersey on October 4 and a search for "Halloween in NYC" on October 15.
Around 2:06 p.m. Tuesday, Saipov rented the truck used in the attack from a store in Passaic, New Jersey, previously identified as Home Depot.
On October 22, he rented a truck from the same store so he could practice making turns before the attack, according to the complaint.
Saipov said he chose Halloween because he thought there would be more people on the streets for the holiday, the complaint states. He hoped to make it as far as the Brooklyn Bridge.
But he decided against displaying a flag in the truck so he would not draw attention to himself, he told investigators. During the interview at Bellevue Hospital, Saipov asked to hang an ISIS flag in his hospital room, saying "he felt good about what he had done," the complaint states.
When an officer shot Saipov, he dropped a paintball gun, a pellet gun and a black bag, the complaint says. The bag contained three knives and a wallet with a Florida driver's license. Law enforcement also recovered a document containing Arabic and English text about 10 feet from the driver's door.
Law enforcement recovered two cellphones and a stun gun from the truck's floor near the driver's seat, the complaint says.