The woman complained that a man at Caldwell Woods was questioning her citizenship and telling her she shouldn't be wearing the shirt.
[Ads /]
Puerto Rico is a U.S. commonwealth. A video of the June 14 incident has since gone viral and shows the officer on scene did not respond.
Later, more officers arrived and arrested the man, who was described as drunk.
Caldwell Woods is part of the Forest Preserves of Cook County. The agency tweeted Monday that an investigation of the officer is ongoing. It says all visitors should feel safe.
[Ads /]
Ricardo Rossello, the governor of Puerto Rico, wants the officer fired.