Diante Speed was convicted earlier this year of firing the shots that killed PhD student Shane Colombo.
Colombo was hit by stray bullets in September 2018 just hours after moving to the city for school.
Colombo was rushed to St. Francis Hospital in Evanston, but was pronounced dead soon after arriving.
Speed was charged in August 2019, almost one year after the shooting happened.
A break in the case came when South Holland police recovered the 9-mm handgun used in the shooting during an arrest in the south suburb, prosecutors said.
The man found in possession of the gun told authorities he bought it from Speed's friend, and the friend allegedly told investigators that he got the gun from Speed.