An Ohio State University student who injured 11 people when he attacked pedestrians on campus with a car and a knife traveled to the Washington D.C. area days before Monday's assault, a law enforcement source told Fox News.
The source said Abdul Razak Ali Artan, 18, arrived late on Nov. 24 and left the following day. The short duration of the trip suggested his visit was "purposeful," the source added.
FBI agents are now seeking court approval to get records from Artan's phone and Internet service provider, which can help determine where he travelled in the D.C. area and whether he contacted anyone.
Artan was shot and killed by a university police officer shortly after he began his attack Monday. Because of Artan's death and the lack of evidence that he was connected to a larger group, the FBI's requests are being processed through regular channels.
Investigators confirmed earlier Wednesday that Artan "may have been inspired" by the ISIS terror group, though they aren't aware of any direct contact between ISIS and the attacker.
Angela Byers, the FBI special agent in charge of the Cincinnati division, said investigators have not found evidence that anyone else was involved in the attack or the planning of it.
Authorities are trying to piece together a gap of several hours between the time Artan bought a knife at a Wal-Mart near his home and the attack. Police don't know if that was the same weapon he used on campus, investigators said.
In a series of Facebook posts hours before the attack, Artan praised American-born Al Qaeda cleric Anwar al-Awlaki as a “hero” and warned of more Muslims in sleeper cells.
Al-Awlaki has been cited as inspiration by numerous terror suspects over the years, including the brothers who bombed the Boston Marathon, the Army psychiatrist who killed 13 people at Fort Hood, Texas, and, more recently, the man charged in bombings in New York and New Jersey.
Rep. Adam Schiff, D-Calif., the ranking member of the House Intelligence Committee, told the Associated Press it seems clear Artan was radicalized online.
He also said there doesn't seem to be much time between the onset of Artan's apparent radicalization and the attack, a period known in law enforcement and intelligence circles as "flash to bang." That trend has disquieted law enforcement officials, who fear disaffected individuals are being inspired to violence after being only briefly exposed to radical ideology.
"This may be one of those cases which was just unpreventable," he said, adding that there was no evidence yet to suggest Artan had been publicly communicating radical intentions over a long period of time.
He said the fact that Artan may have been inspired by a cleric killed five years ago shows the "limits of taking people off the battlefield."
"As long as you have disaffected or alienated young people who are searching for something to belong to, the lure of this radical propaganda will continue to be very dangerous," Schiff said.
Fox News' Catherine Herridge and the Associated Press contributed to this report.