Police identified the man suspected of killing at least eight people and injuring 11 others when he plowed a truck down a bike path in Manhattan on Tuesday as Sayfullo H. Saipov.

Saipov — who police officially identified for the first time on Wednesday — appears to have followed “almost exactly to a 'T’ the instructions that ISIS has put out in its social media channels” on how to carry out such an attack, Deputy Commissioner of Intelligence and Counterterrorism for the NYPD John Miller said, citing notes and other evidence found in the rented Home Depot truck.

The notes, he added, were handwritten in Arabic, and included symbols and words.

“The gist of the note was that the Islamic State would endure forever,” Miller said.

The evidence also made clear that Saipov had planned the attack for weeks “in the name of ISIS," Miller added.

Miller said that Saipov himself was never the subject of a NYPD or FBI intelligence investigation, but that it appears he was connected to people who were.

"What we are looking for is how he has touched the subjects of other investigations, what is his connectivity to those people, and we're kind of building out concentric circles to try to document that," Miller said.

Saipov was interviewed as a "person of contact" for two men who were on the Department of Homeland Security's counterterrorism databases, ABC News reported citing an unnamed federal official.

One of the men was flagged after arriving from a "threat country," according to ABC News.

Saipov, who was born in Uzbekistan, has lived in Ohio, Florida, and most recently Paterson, New Jersey. He has a wife and three children, the FBI confirmed to BuzzFeed News.

Saipov became a permanent US resident in 2010, entering the US with a green card under the Diversity Visa Program, according to ABC. The program is a lottery system for people from countries with low rates of immigration to the US.

Saipov, who had a Florida driver's license, was employed as an Uber driver. A company spokesperson confirmed to BuzzFeed News on Tuesday that he passed a background check and has since been banned from the app.

In a statement, the company said it is "horrified by this senseless act of violence" and has "reached out to law enforcement to provide our full assistance.”

Records in Summit County, Ohio, show a marriage license certified to a Sayfulloh Saipov, then 25 years old, and Nozima Odilova, then 19, in April 2013. The license identifies Saipov’s birthplace as Tashkent, Uzbekistan, and notes “truck driver” as his occupation.

Dilnoza Abdusamatova, 24, told the Washington Post that Saipov stayed with her family in Cincinnati for two weeks after he arrived in the US because their fathers knew each other. She said that he moved to Florida to start a trucking company and that he got married around a year after coming the US, around which time he stopped talking to Abdusamatova's family.

One of his neighbors in the apartment complex in Paterson told NJ.com that Saipov was unfriendly and never greeted him. He "never says good morning and never says good afternoon," Slavo Petrov said.

A longtime Uzbek-born acquaintance told Radio Free Europe that Saipov had had verbal clashes with others in the Uzbek immigrant community and was a "little aggressive."

The acquaintance, Mirrakhmat Muminov, told the outlet he met Saipov shortly after he arrived in Ohio in 2010. Muminov said Saipov was not religious when they met and attended mosque "once [in] a while."

"No one understands how he became a terrorist," he said.

Muminov last spoke with Saipov two months ago, he told Radio Free Europe, and last saw him in Ohio about two years ago.

Another acquaintance, who asked not to be identified, told RFE/RL's Uzbek Service Wednesday that he had had "an argument on a religious issue" with Saipov several months ago, that he appeared to hold "radical views," and that he seemed to be depressed and isolated.

Muminov said the Uzbek community in Stow, Ohio was shocked by the news.