Ms. Dunton was initially charged in December, and if convicted, faces up to 10 years in prison.
While working at the ASC, Ms. Dunton allegedly took vials of fentanyl and self-administered them by injection.
According to the indictment, she removed liquid fentanyl from nearly 450 vials, filled them with saline and returned the tainted vials for use during surgical procedures.
Her sentencing is set for June 27.
