Police released a sketch of the man they're looking for.
Investigators say he followed the girl into her apartment building in Elmhurst on Saturday, touched her sexually, and then exposed himself.
The girl ran away.
The suspect is described as a white male, approximately 30 years old, 5'10" to 6'00", 170 to 190 lbs., bearded, wearing a black sweat suit, a black knit cap and glasses.
He was also pushing a black mountain bike.
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