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NORMAN, Okla. – Day eight of a trial against a man accused of a horrific workplace attack was devoted entirely to a psychologist who testified the suspect is suffering from schizophrenia.

Dr. Anita Jeanne Russell, a Tulsa-based psychologist, is one of four witnesses who have been called to testify by Alton Nolen’s defense attorneys. Nolen is on trial for beheading his coworker Colleen Hufford and attacking Traci Johnson in September 2014 inside Vaughan Foods.

Hufford died from her injuries, however Johnson survived. She was one of more than 20 witnesses called to the stand by state prosecutors during the first three weeks of trial.

Russell first began her testimony Tuesday afternoon. Russell met with the suspect in 2015 for an evaluation.

“I found him to be quite delusional,” she told told the courtroom Tuesday.

On Wednesday, Russell continued her testimony explaining to court the legal definition of ‘insane’ in Oklahoma includes: Does someone have a mental illness? If so, does he/she know between right and wrong?

Based on her evaluations, Russell said she believes Nolen was insane during the time of the incident.

During cross examination, she was questioned by assistant district attorney Susan Caswell who referred to a past test conducted on Nolen. Part of the criteria included his interaction with his attorneys, which indicated he did not show any odd communications, disorganized speech, or delusions.

The defense has also called psychiatrist Dr. Antoinette McGarrahan, religion professor Dr. Robert Hunt, plus a practicing Muslim who has met Nolen at a mosque during a prayer service.

McGarrahan also maintained she believes Nolen is suffering from a mental illness.

The defense will officially rest Thursday morning, when state prosecutors will have a chance for a rebuttal. Cleveland County District Attorney Greg Mashburn said they plan to present three witnesses, including two doctors.