The 19-year-old suspect being held in the New Year's Eve machete attack on three police officers at Times Square was on an FBI terror watchlist, CNN reported.
The family of Trevor Bickford, reported him to the Wells, Maine, police department in December after he said he wanted to join the Taliban. He had indicated he wanted to travel overseas to help fellow Muslims, and he was placed on a terrorist watch list after the FBI interviewed him.
New York City police said Bickford walked up to an officer at about 10 p.m. Saturday and, unprovoked, attempted to strike him with the machete, and then hit two other officers on the head with the weapon. One of the officers then shot Bickford in the shoulder, wounding him, according to police.
The officers were released from the hospital on Sunday. The suspect is being held under guard at Bellevue Hospital.
Law enforcement sources told ABC News that authorities are not ruling out the possibility that the suspect came specifically to New York City to attack police officers at the Times Square ball drop. It is being probed as a possible terrorist attack.
The sources told ABC that investigators are combing through the suspect's online postings, which indicate recent radicalization by extremist Islamic groups. According to authorities, the attack would be the first terror incident associated with New Year's Eve in Times Square if it was indeed motivated by Islamist ideology.
As part of a pre-event assessment, the NYPD reported that throughout December "multiple pro-ISIS users disseminated extremist propaganda graphics broadly calling for attacks in advance of the New Year, advocating a wide range of low-tech tactics," ABC reported, noting that knife attacks have long been promoted by Islamist terror groups.
According to multiple law enforcement sources, FBI agents interviewed Bickford in Maine in mid-December after he said he wanted to travel overseas to help fellow Muslims.
According to the sources, Bickford's mother and grandmother became increasingly concerned about his desire to travel to Afghanistan to join the Taliban and reported the matter to local police department.
The FBI put Bickford on a terrorist watchlist after opening a larger probe, sources told ABC.
The U.S. government has not designated the Taliban as a foreign terrorist entity, so planning to travel to Afghanistan to join the group does not constitute a federal crime of "attempted material support of a terrorist group."
A diary police believe belongs to the suspect includes a final will and testament. The final entry, dated Dec. 31, begins, "This will likely be my last entry," and goes on to explain how the author's belongings will be divided among his family and how he should be buried, sources told ABC.