Admitted murderer Alton Alexander Nolen is escorted Friday to the Cleveland County courthouse for another hearing on his mental state. [Photo by Steve Sisney, The Oklahoman]

NORMAN — The Muslim convert who beheaded a co-worker at a Moore food plant in 2014 had an ISIS flag in his car, a prosecutor revealed Friday during a hearing on his mental competency.

Alton Alexander Nolen, 31, also had researched on his computer ISIS and beheadings, Cleveland County District Attorney Greg Mashburn said.

Nolen pleaded guilty in May to first-

degree murder for beheading the co-worker. He also pleaded guilty to assault and battery with a deadly weapon for trying to behead another co-worker and to assault with a dangerous weapon for confronting a plant official with a knife.

He wants to be sentenced to die by lethal injection. First, though, Cleveland County District Judge Lori Walkley must decide whether to accept his plea.