A former Pennsylvania casino worker and a Nevada high school student have pleaded not guilty to charges in a Uganda-based scheme that produced more than $1.5 million in high-quality counterfeit U.S. bills.

Twenty-year-old Michael Lin, of Bethlehem, and 18-year-old Zackary Ruiz, of Las Vegas, appeared Wednesday before a federal magistrate in Pittsburgh.

They and two others are charged with conspiring to commit offenses against the United States, specifically counterfeiting, among other crimes.

According to the indictment, Ruiz bought and distributed fake U.S. currency that was printed and shipped to him.

The indictment says Lin received and passed some of the bills and wrote a guide detailing how he passed counterfeit Federal Reserve notes at casinos.

The defendants and their attorneys declined to comment.