OKLAHOMA CITY (AP) — The Oklahoma Court of Criminal Appeals on Thursday upheld the murder conviction and death sentence of man in the beheading of a co-worker in the Oklahoma City suburb of Moore.

The court rejected claims that Alton Alexander Nolen, 36, was mentally ill and incompetent to stand trial in addition to improper jury selection, improper photographic evidence and prosecutorial misconduct.

Nolen’s defense attorneys did not immediately return a phone call for comment.

Nolen was convicted and sentenced to death in for the 2014 beheading of 54-year-old Colleen Hufford at Vaughan Foods.

Prosecutors said Nolen killed Hufford and wounded another co-worker after being suspended from his job at the plant for making threatening statements to co-workers.