Police were called to the river near the 600 block of South Wells Street about 2:45 p.m., and found the body of a white male, police News Affairs Officer Joshua Purkiss said.
The man, believed to be in his 40s, remains unidentified Wednesday night, according to the Cook County Medical Examiner's office.
The medical examiner tells ABC 7 Chicago that the body has not yet been identified because it is decomposed.
Authorities could not immediately say how he was found, or how he came to be in the river. An autopsy is scheduled for Thursday.
Area Central detectives are investigating.
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