(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 started planning an attack in the United States about one year ago

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.

He was inspired by ISIS videos to use a truck

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."

A screen grab from an ISIS video released in 2014 that purports to show Abu Bakr al-Baghdadi.

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.

He rented a truck before the attack to practice

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.

Officials prepare to tow the Home Depot rental truck from the scene.

He said he wanted to kill as many people as possible

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.

The New York Halloween parade went on Tuesday despite the attack in another part of town.

He wanted to display ISIS flags in the truck and his hospital

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.

Several items were collected from the area where Saipov was shot

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.

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Items were found inside the truck, too

Law enforcement recovered two cellphones and a stun gun from the truck's floor near the driver's seat, the complaint says.