A man accused in the stabbing death of a coworker in Cass County entered a Not Guilty plea on Wednesday.

William Henderson of Elkhart appeared in court Wednesday. He said the man he killed, Juan Mendez of Elkhart, had disrespected him on several occasions at work, and expressed little emotion in court, according to ABC 57.

He also said he admitted to hearing voices.

Cass County Prosecutor Victor Fitz says Henderson’s mental health could be used as a defense. Fitz says given the witnesses and evidence in this case, he expects to pursue a charge of first degree murder.

had previously admitted to killing Juan Mendez while working at Ameri-Kart. He had claimed that it was his duty to kill Mendez because they were in rival gangs.