As U.S. prosecutors rest their case against Mexico's former top cop during a trial in New York City, another question is in play: Are U.S. efforts to stem the flow of deadly Fentanyl from Mexico into the United States doing any good?
Four years ago, the conviction of Joaquín "El Chapo" Guzman Loera gave prosecutors many other threads to pull on the web of crime and corruption that enables the transnational drug trade.
