The Will County Coroner's Office identified the dead youth as Anthony Hernandez, 16.
Hernandez was struck by "multiple" vehicles while on foot in the northbound lanes of I-55 near the Jefferson Street exit.
Hernandez was run down shortly before 2 a.m. and pronounced dead at the scene soon after.
An autopsy conducted Monday showed Hernandez suffered "multiple injuries." The cause and manner of his death will not be determined until toxicological testing and the police investigation are completed.