The bedroom of a luxurious Mexicali residence a block from the border hid a secret tunnel leading to neighboring Calexico, Mexican officials said yesterday. Inside the passageway, investigators discovered lighting and ventilation equipment, a closed-circuit security system, hydraulic machinery and various tools, according to a statement yesterday by the Mexican Federal Attorney General's Office, or PGR. The findings led agents to surmise that "the tunnel was used for illicit activities, presumably related to drug trafficking," the statement said. A middle section of the passageway was initially discovered in the United States early Friday by U.S. Border Patrol agents checking for...