McLean County authorities say Coprich has been preliminarily charged with felony distribution of 10 to 30 grams of marijuana. Court records indicate he hasn't yet been arraigned or entered a plea.
Coprich is free on $2,025 bail.
Illinois State coach Brock Spack said in a news release that Coprich has been suspended for an unspecified violation of team rules, but didn't elaborate.
Coprich was a College Football Championship Subdivision All American last fall. He set school records with 2,274 yards rushing and 27 rushing touchdowns.