John Madinger has dedicated his career to fighting the drug war, serving as a sheriff's deputy, narcotics agent, and special agent with the U.S. Department of the Treasury. His previous works include the memoir "Going Under: Kidnapping, Murder, and a Life Undercover and he joins me today to talk bout his latest book, LETHAL DOSES: The Story Behind 'The Godfather of Fentanyl, delves into the life of George Erik Marquardt.