Prosecutors have agreed not to seek the death penalty, and in return Yvonne Hiller is no longer seeking an insanity plea in the double-murder case.
The 45-year-old Hiller has allegedly told police she thought co-workers at a Kraft Foods plant were spraying her with deer urine.
Police say she was suspended after a confrontation in September 2010, left the plant and got a gun, and returned minutes later.
They say she targeted two workers, killing two and injuring a third.
At the time, about 100 people worked at the plant, making Nabisco cookies and crackers.
Common Pleas Judge Benjamin Lerner will hear the case.