Signage is seen at the United States Department of Justice headquarters in Washington, D.C., August 29, 2020.Andrew Kelly | ReutersFederal prosecutors in Brooklyn have charged the founder of a U.S.-based cryptocurrency payments firm with operating what they allege was a sophisticated international money laundering scheme that moved over half a billion dollars on behalf of sanctioned Russian banks and other entities.Iurii Gugnin, a 38-year-old Russian national living in Manhattan, was arrested an...