A former longtime Drug Enforcement Administration agent who rose to help oversee the agency’s financial operations has been charged with agreeing to launder millions of dollars in narcotics proceeds for a Mexican drug cartel, according to an indictment unsealed Friday in U.S. District Court in the Manhattan borough of New York City. The former agent, Paul Campo, worked for the DEA for about 25 years, the indictment said, first as a special agent in New York and eventually rising to become a high-level official — the deputy chief of the Office of Financial Operations. He retired in January 2016 and...