[...] postings on the Facebook page of the 30-year-old Nolen, suspected of beheading a woman at an Oklahoma food distribution center, suggest that shortly after his release in March 2013, he became more interested in spreading the message of his newfound Islamic faith. Moore Police Sgt. Jeremy Lewis said Nolen, who had just been fired from the company, walked into the facility's administrative office and attacked Hufford with a large knife, eventually severing her head. Nolen then repeatedly stabbed 43-year-old Traci Johnson before he was shot by Mark Vaughan, a reserve sheriff's deputy and the company's chief operating officer, police said. Oklahoma prison records show Nolen was released from prison after serving two years of a six-year sentence on charges that included assaulting a police officer and possession of cocaine with intent to distribute. Lewis said police asked the FBI to look into Nolen's background because of the nature of the attack, which followed a series of high-profile videotaped beheadings by Islamic State militants in the Middle East.