PROVIDENCE, R.I. — A woman who lost her job at Twin River casino is blaming Rhode Island State Police, alleging in a lawsuit that the agency retaliated against her for refusing to serve as an informant.

The Rhode Island chapter of the America Civil Liberties Union sued state police Wednesday on behalf of Marissa Lacoste, of Warwick.

The ACLU says detectives stopped Lacoste in January with less than an ounce of marijuana. They told her she was in serious trouble, even though it’s not a crime to possess that amount. She cooperated until February.

The federal lawsuit says police then told Twin River she was banned from entering the casino, preventing her from working there.

A state police spokeswoman says the agency takes allegations against it seriously but doesn’t comment on pending litigation.