Will County Sheriff's Office said last week, deputies were called to a home in the 12200-block of West Thorn-Apple Drive about an unresponsive child.
They found two year-old Trinity Balen-Weiher, who later died.
Officers said they discovered heroin, rotten food, and soiled clothing inside the home.
Trinity's parents, Edward Weiher and Alexa Balen, now face charges, including endangering the life of a child.
Their six-year-old child was in the home at the time and has been placed in custody of the Illinois Department of Children and Family Services, the Will County Sherriff's Office said.
Trinity's cause of death is still being determined.