CHICAGO β€” Cook County is suing Facebook and Cambridge Analytica for allegedly violating an Illinois fraud law after reports that the political consulting firm used ill-gotten Facebook data in an effort to influence voter behavior.

Cambridge Analytica, which was hired by President Donald Trump’s campaign, deceived the millions of Illinois Facebook users whose information it collected, alleges the lawsuit, filed Friday in Cook County Circuit Court. And Facebook failed to protect its users’ privacy and misrepresented how their data would be used, the lawsuit says.

“(Facebook) sought to keep developers building on its platform and provide companies with all the tools they need to influence and manipulate user behavior,” the suit complaint says. “That’s because Facebook is not a social media company; it is the largest data mining operation in existence.”

The lawsuit joins others brought against the social media giant and Cambridge Analytica in response to a report from The New York Times and The Observer of London earlier this month. The newspapers reported that Cambridge Analytica, whose U.K.-based parent SCL Group was also named in Cook County’s suit, gained access to private information of more than 50 million Facebook users, including their profiles, locations and what they like. The firm claimed its tools could analyze voters’ personalities and influence their behavior with targeted messages.

Since the report, a public movement to delete Facebook has sprung up, and the privacy of people’s online information has come into question. Some experts say that deleting a Facebook profile can’t protect the decade’s worth of data users have already poured into the platform.

The Federal Trade Commission opened an investigation into Facebook, and U.K. investigators raided Cambridge Analytica’s offices in London, according to reports.

Facebook CEO Mark Zuckerberg promised in a post last week that the company would do more to protect its users’ data. “We have a responsibility to protect your data, and if we can’t then we don’t deserve to serve you,” he wrote.

Cambridge Analytica improperly acquired the information, Facebook has said, but it didn’t steal the data. Users allowed the maker of a personality quiz app to take the data. About 270,000 people took the quiz several years ago, and the app-maker was able to scrape data from their Facebook friends. He then provided the data to Cambridge Analytica.

Still, Facebook told its users that their personal data would be protected, according to the Cook County lawsuit. It company engaged in unfair and deceptive conduct when it allowed a third party to collect its users’ data, the suit alleges.

The lawsuit, filed by Cook County State’s Attorney Kimberly Foxx on behalf of the people of Illinois, brings one count each against Facebook and Cambridge Analytica for allegedly violating the Illinois Consumer Fraud and Deceptive Business Practices Act.

The suit asks that both companies be fined $50,000 for each violation of the law and that Cambridge Analytica be fined an additional $10,000 for each day a violation affecting an Illinois resident age 65 or older has existed.

Cook County representatives did not immediately return requests for comment. Cook County is being represented by Chicago law firm Edelson, which has brought privacy suits against Facebook and other tech companies, including Google and Netflix.

Neither Facebook nor Cambridge Analytica responded immediately to requests for comment on the lawsuit.

Cambridge Analytica has denied any wrongdoing and suspended its CEO, Alexander Nix. The app developer, Cambridge University researcher Aleksandr Kogan, who is not named in the Cook County suit, told the BBC last week that he didn’t know the data would be used for Trump’s election campaign and that Cambridge Analytica is using him as a scapegoat.