NORMAN, Okla. (AP) — A psychiatrist has testified that an Oklahoma man charged in the beheading of a co-worker was insane at the time of the attack.

Alton Nolen is on trial for first-degree murder and five counts of assault in the Sept. 25, 2014, attack at Vaughan Foods in Moore that killed 54-year-old Colleen Hufford. He is also accused in the attempted beheading of another co-worker.

Psychologist Jeanne Russell testified Tuesday for the defense that the 33-year-old Nolen was mentally ill at the time and is getting sicker.

Prosecutors contend Nolen knew right from wrong and are seeking the de...