Authorities have uncovered no links to terrorism for Oklahoma native Alton Nolen, 30, who was charged Tuesday with murder and assault with a deadly weapon after beheading a coworker last week. 

The FBI analyzed a number of Nolen's electronic devices, according to The New York Times. The review found that he looked at a number of religious material — including the Bible and other al Qaeda material — but found no link to foreign terrorism. 

Officials told the newspaper they were still analyzing the material to see if he communicated with any foreign terrorist group. Reports had indicated he was a recent convert to Islam.

Nolen was charged Tuesday with first-degree murder in the decapitation of co-worker Colleen Hufford at a food processing plan in Oklahoma. He was also charged with assault and battery with a deadly weapon for stabbing another co-worker Traci Johnson. He was charged with a third count of assault with a deadly weapon as well. 

The graphic details of the murder came weeks after the terrorist group Islamic State in Iraq and Syria released videos depicting the beheading of two U.S. journalists and a British aide worker. 

Officials have said the Oklahoma attack at Vaughan Foods was likely triggered after Nolen was suspended from the job for making a remark disparaging white people. After learning that he was suspended, officials said, he went to his home to pick up a kitchen knife and returned to the plant. 

He was eventually stopped when the company’s chief operating officer shot him.