A judge in Oklahoma refused to accept a guilty plea from a man accused of beheading a co-worker at a food processing plant in 2014.

Cleveland County District Judge Lori Walkley ruled Wednesday that she wouldn't accept the plea from Alton Nolen, who has said he wants the death penalty for the attack at Vaughan Foods in Moore. Walkley said Nolen was not mentally competent to make the plea and ordered another mental evaluation.

Nolen entered the guilty plea to a first-degree murder charge in the beheading of 54-year-old Colleen Hufford shortly after he was suspended from the company for making racial remarks.

District Attorney Greg Mashburn told Oklahoma City television station KFOR that he believes Nolen is mentally competent and he hopes the delay won't be lengthy.