Columbus Police and the FBI say an ongoing investigation into Monday's attack at Ohio State still has hours unaccounted for in its timeline of events.
In a press conference Wednesday afternoon, authorities said that Abdul Razak Ali Artan bought a knife at Walmart on the morning of the attack. They are also looking into a Facebook post allegedly written by him from that same morning about U.S. interference in Muslim lands.
"It's that time in-between the purchase and the arrival on campus that we need to fill in," said Columbus Police Deputy Chief Michael Woods.
Authorities are requesting any information people might have about Artan's whereabouts and actions during that time period.
FBI agent Angela Byers says the Facebook post is one piece of evidence that has led them to believe Artan, a Somali-born OSU student, may have been influenced by extremist ideology and the tactics of the Islamic State. But officials say it is too soon to call the attack an act of terrorism.
While ISIS website claimed responsibility, Byers says, that does not indicate a link.
"[ISIS] have been known to take credit for incidents like this when the assailant is deceased and cannot refute that," she says.
Law enforcement officials say Artan had no criminal record and was not on a terrorist watch list. They believe he acted alone.
A separate investigation is being conducted into the use of deadly force by Ohio State officer Alan Horujko. Police say Horujko told Artan several times to drop his weapon before firing shots. A stray bullet, believed to have been fired by the officer, hit a bystander in the foot.
Preliminary autopsy results were released Wednesday by the Franklin County Coroner's office. The report says Artan was killed by gunshot wounds to the head and chest.