NORMAN, Oklahoma - Closing arguments and jury deliberations are expected to begin Friday in the murder trial against Alton Nolen, three years after the deadly beheading at Vaughan Foods in Moore.

This is a death penalty case, which means, if Nolen is found guilty, phase two of the trial would happen next week where he'd learn if he gets life with or without parole, or the death penalty.

This week, the defense put on their case. Jurors heard from two psychologists who diagnosed Nolen with schizophrenia and said he was insane when he beheaded Colleen Hufford in 2014. 

The state disagreed, bringing in two of their own psychologists. 

One doctor who evaluated Nolen prior to the trial said he found no signs of mental illness. 

He said while Nolen maintained strong religious beliefs, he was not religiously delusional. 

A second doctor, who Nolen refused to see in person, said he made his determination after reviewing thousands of documents and records.

He disagreed with the schizophrenia diagnosis and said Nolen instead has a personality disorder with antisocial traits. 

He said with this diagnosis, Nolen still had the ability to understand the beheading was illegal.

If Nolen is found guilty, the punishment phase would begin on Monday