Federal authorities have been aware of the alleged attacker, 20-year-old Wasil Farooqui of the Roanoke area, for some time, sources familiar with the case told ABC News. In the past year, sources said, he traveled to Turkey and may have tried to sneak into Syria, where ISIS is recruiting and inspiring sympathizers from around the world.
Farooqui was arrested Saturday by Roanoke County Police on charges of assault with malicious wounding, and he is being held without bond at the Western Virginia Regional Jail, according to the sources and a jail database.
On Saturday, Farooqui allegedly injured a man and woman at an apartment complex in Roanoke, yelling "Allahu akbar" -- God is great -- as he attacked them with a knife, sources told ABC News.
Authorities believe he may have been trying to behead the male victim, who was likely picked at random, ABC News was told. But on Tuesday -- after news of the case surfaced nationwide -- a spokeswoman for the Roanoke County Police said that while the male victim was cut "all over his body, including his neck," police do not believe the case looks like a beheading attempt.
Asked whether Farooqui may be suffering from mental illness, the spokeswoman declined to comment.
Farooqui and his two alleged victims were hospitalized after the attack. Their conditions were not clear.
"The FBI is working with the police department following the incident that occurred on Saturday evening," Adam Lee, the head of the FBI's Richmond field office and the special agent in charge, said in a statement. "While I cannot discuss details of the investigation at this time, I do want to reassure the community that we are working to determine the nature of the incident."
ISIS has released several propaganda videos showing the beheadings of Western journalists and others.
It was not clear whether Farooqui has a lawyer.