In April 2009, Mexico's ruthless Gulf Cartel had a Baltimore problem.
Officers with the Drug Enforcement Administration had found an associate of the cartel in an Inner Harbor hotel room with more than $600,000 in alleged drug proceeds.
When the officers seized the money, prosecutors say, the cartel wanted answers. But the man they sent to investigate would himself be busted by the FBI.
Alex Mendoza-Cano would turn informant — and federal prosecutors say his testimony in U.S. District Court this week against two men charged in a cocaine conspiracy provides insight into how Mexican cartels are operating in Baltimore and other U.S. cities.
Assistant U.S. Attorney...