Authorities are investigating the death of a 1-year-old girl Monday afternoon in south suburban Chicago Heights.

About 1:25 p.m. on Oct. 1, the girl was pronounced dead at Comer Children’s Hospital, according to the Cook County medical examiner’s office.

She died from an unknown incident at her home, 182 E. 25th St., the medical examiner’s office said. The results of an autopsy conducted Thursday were pending.

On Sunday, a day before the death, the Illinois Department of Child and Family Services opened an investigation into the girl’s mother for allegations of inadequate supervision and death by neglect, a spokesman said. The investigation was pending Friday.