Jury selection began earlier this week in the case of Alton Nolen, the man accused of beheading one employee and attempting to kill another at Vaughan Foods in Moore, Oklahoma. 

Three years ago, on September 25, 2014, a recently-fired Nolen left the facility and quickly returned to another part of the building armed with a "standard knife" of the same type used at the food processing plant. He attacked Colleen Hufford, 54, in a front office, decapitating her with a knife. He then attacked another former co-worker, Traci Johnson, 43, stabbing her several times. 

The assault continued until Mark Vaughan, president and chief operating officer of Vaughan Foods and an Oklahoma County Sheriff's Office reserve deputy, shot Nolen.

Since then, Nolen has repeatedly tried to plead guilty to the murder and assault and has asked for the death penalty. However, Cleveland County District Judge Lori Walkley has repeatedly declined to accept his guilty plea amid concerns about his mental competency.

Nolen's defense team has argued that the defendant is mentally incompetent and unable to assist in his own defense. Rather than helping them build a defense, they say, he merely pleads guilty. They argued that he is not competent to stand trial.

However, at a mental competency hearing in April, a judge noted the following:

“The evidence indicated that he was able to graduate from high school, play interscholastic sports, gain admission to and attend college, socialize and communicate effectively, work, make efforts to seek higher employment, undertake religious studies, plan and execute goals and live independently. Therefore, it is the finding of this Court that Defendant does not meet the statutory definition of mental retardation.”

The judge found Nolen competent to stand trial, but at that hearing, the defendant refused to reaffirm his guilty plea. Cleveland County District Attorney Greg Mashburn said that Nolen refused to even acknowledge the questions posed to him at that hearing, so the case had to go to trial.

Nolen's attorneys say they plan to use the insanity defense in Nolen's trial.