Police say a man approached a woman at the Red Line station at State and Lake on Sept. 3 at about 9 p.m.
CPD said the suspect grabbed the woman's behind without her consent.
This comes as police also issued a warning after multiple cases of sexual abuse in the Avondale neighborhood on Sept 11.
READ MORE | Man wanted for sexually abusing women in Avondale, Chicago police say
In another incident, police said another man sexually abused a woman at a CTA Blue Line Cumberland Station on Sept. 5.
RELATED | Chicago police issue alert on sexual abuse at CTA Blue Line station in Wicker Park
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