About 1 a.m., a CTA employee found the man unresponsive while walking down the stairs to the Blue Line platform in the 500 block of South LaSalle Avenue, Chicago police said.
The man, about 30 to 35 years old, was pronounced dead at the scene, police said. He had no evident signs of trauma, according to police.
The Cook County medical examiner’s office hasn’t released details on his death.
Area Three detectives are investigating.