Authorities say Brittney Stafford fell from the building around 5 a.m. Saturday.
The medical examiner ruled her death an accident Sunday.
Chicago police spokeswoman Antoinette Ursitti says detectives are conducting a death investigation into how the woman fell several stories.
Stafford, whose family lives in Indianapolis, was a graduate of Indiana University. Her brother Eric Stafford tells the Chicago Tribune that she was at a friend's house.