"Later, they figured it was easier to build tunnels into the drainage system that traversed the US-Mexico border, because it saves a lot of time and saved a lot money," Vigil told Business Insider. "So what they would do is build the tunnel, hit the drainage system, and then use that drainage system to come up on the US side."
A drain exit that leads to a tunnel underneath one of the houses of Joaquin "El Chapo"Guzman is seen in a neighborhood in Culiacan, in Sinaloa state, February 25, 2014. Guzman, who rose from humble origins to become one of the most powerful drug barons in history, was captured in a raid in the beachside resort and fishing center of Mazatlan, 125 miles southeast of Culiacan, just days after escaping from the clutches of Mexican troops through a tunnel and sewers in early 2014.