By Kristina Davis The San Diego Union-Tribune SAN DIEGO—As Mexican and U.S. forces closed in on Joaquin “El Chapo” Guzmán Loera in the winter of 2014, they set out first to find the man they hoped would unlock many of the drug kingpin’s secrets, and ultimately his whereabouts. Characterized as Guzmán’s personal assistant, Mario Hidalgo Arguello was intricately involved in the fugitive’s comings and goings. Hidalgo’s nickname in the Sinaloa cartel was “El Nariz,” named for his prominent nose, which made him easily identifiable when authorities tracked him down at a party in Culiacán one night and demanded a tour of Guzmán’s hideouts. Indeed, Hidalgo led the Mexican Marines and a U.S. drug agent to the safe house where Guzmán was holed up, but he narrowly escaped through a tunnel under the bathtub. Still, authorities stayed on the trail, capturing Guzmán a week later at a Mazatlán hotel. While Hidalgo’s …