NEW YORK -- The suspect in Tuesday's deadlyin New York City was known to U.S. authorities because his name was associated with the subjects of other FBI counterterrorism investigations in 2015, an intelligence source said, CBS News' Pat Milton reports.
The intelligence source said the suspect, 29-year-old, had some contact with those individuals, who were considered radicalized extremists. One of the individuals was Uzbek, like Saipov.
It is unclear whether the individuals under investigation at the time were in the United States or overseas. Saipov was not the main focus of the investigation. It is unclear if he was interviewed by the FBI at the time.
Earlier Wednesday, police said Saipov had been planning the attack that killed eight people Tuesday "" and closely followed .
Saipov, a truck driver and Uber driver, had a handful of traffic violations and was arrested last year in Missouri after failing to appear in court on a citation for brake defects. Jail records indicate he was held for less than an hour.
After Tuesday's attack, Saipov told police from his hospital bed that he's pleased with his actions and is unapologetic for the attack, sources tell CBS News. One source said, which .
Investigators also discovered 10 to 15 pieces of paper with. One note said "ISIS will endure," sources say.
Authorities also recovered knives at the scene, although they were not used in the attack.
Saipov was allegedly driving a Home Depot rental truck when he deliberately steered onto a bike lane along Manhattan's West Side Highway, not far from the World Trade Center site. He drove for several blocks, running down pedestrians and bicyclists, before slamming into a school bus and coming to a stop. Police say he exited the vehicle and shouted "God is great" in Arabic before beingand taken into custody.