The Dec. 22 crash on the Dan Ryan Expressway killed the 4-year-old from League City, who died from head trauma.
The Chicago Sun-Times reports prosecutors say 46-year-old Franklin L. Jackson didn't notice the boy was missing until he pulled into a gas station to examine the vehicle's damage.
The preschooler wasn't wearing a seatbelt. He was found on an embankment.
Three other children - all under 2 - weren't injured.
Jackson is charged with reckless homicide and aggravated driving under the influence. His attorney called the crash "a terrible tragedy" during a court appearance Wednesday.
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