Forty-six-year-old William Ward entered the plea Monday in Lehigh County Court to a first-degree murder charge in the June 2011 slaying of 29-year-old Trisha Sadler.
Public defender Earl Supplee said the plea could help his client end up in a prison designed to house inmates with mental illnesses.
Ward said in court "I'm just sorry for my mental illness."Police arrested Ward after a five-hour standoff at the Bethlehem home where he lived with Sadler, his girlfriend of nine years.
Authorities said in court documents that police found plastic bags containing Sadler's remains in the home.
