Federal terrorism charges were brought Wednesday evening against 29-year-old Sayfullo Saipov, the suspect accused of driving a truck down the West Side Highway bike path yesterday, killing eight people and injuring twelve more.

Saipov allegedly started planning the attack a year ago, and decided to use the truck to target civilians two months ago, according to the complaint. He had planned to continue driving his rental car to the Brooklyn Bridge to continue to strike pedestrians and "kill as many pedestrians as he could," the complaint states.

Saipov has been charged with providing material support and resources to a "designated foreign terrorist organization" as well as violence and destruction of motor vehicles, according to the United States Attorney for the Southern District of New York.

"We don't know his path of radicalization yet," NYPD head of counterterrorism John Miller told reporters.

The complaint summarizes an interview that Saipov gave to investigators from his bed at Bellevue Hospital on Tuesday.

Saipov allegedly said that he was inspired to carry out the attack by ISIS videos that he watched on his cell phone. He was particularly motivated by a video featuring Abu Bakr al-Baghdadi in which the ISIS leader asked what Muslims in America were doing to respond to the killings of Muslims in Iraq.

Saipov rented a truck from Home Depot on September 22nd to practice "making turns," according to the complaint. He allegedly chose Halloween because he believed there would be more civilians on the street, and had initially considered displaying ISIS flags on the front and back of the truck, he said, but decided against it to avoid drawing too much attention to himself.

During his bedside interview, Saipov allegedly asked to display the ISIS flag in the hospital room and said that he "felt good about what he had done," according to the complaint.

According to investigators, a bag recovered from the scene contained three knives, as well as a Florida driver's license. Investigators also recovered two cellphones and a stun gun from the floor of the truck. One cell phone allegedly contains dozens of videos and thousands of images that appear to be ISIS propaganda. A document containing "Arabic and English text" was also recovered about ten feet from the truck, and Saipov allegedly told investigators that he had written it. It reads, in substance, "No God but God and Muhammad is Prophet" as well as "Islamic supplication. It will endure," according to the complaint.

The NYPD and federal prosecutors held a joint press conference Wednesday evening in Manhattan. The top possible penalty for the terrorism charge is life in prison, they said. The top penalty for the federal violence and destruction of motor vehicles is death.

Around the same time, the NYPD announced that they were seeking a second person in connection to Tuesday's deadly attack. Assistant FBI Director Bill Sweeney said at the start of the press conference that the request for information had been redacted, though the man's photo and name were still posted on the FBI's website at that time.