The deputy was identified as James Koch, 51, of Chicago Ridge.
Just after midnight, Koch was driving a 2002 Chevrolet in the 10100 block of Virginia Avenue when he was struck by a 2015 Nissan. The driver of the Nissan was a 16-year-old boy.
WATCH: PROCESSION FOR DEPUTY KILLED
Procession of vehicles for Deputy James Koch
Chicago Ridge police and fire departments responded to the crash and found Koch trapped and unresponsive in his vehicle.
Koch was extricated and was transported to Advocate Christ Medical Center where he was pronounced dead.
The teen driver, who is not being identified, is being held for a juvenile detention hearing on Sunday in Chicago. He faces multiple charges, including reckless homicide.
Investigators said that the teen driver was going much faster than the 25-mph limit and did not have a driver's license.
The Illinois State Police Accident Reconstruction Team is assisting in the investigation.
Koch was on his way home after his shift. He was just a half mile from his house.
Koch was an investigator with the sheriff's department and looking forward to retirement in two years. He had brothers who were a Chicago police officer and an Indiana State Police trooper.
Cook County Sheriff Deputy killed, teen injured in high-speed crash in Chicago Ridge