Drug traffickers purchased the Calexico property in April for $240,000 and finished building a three-bedroom house on the parcel for $86,000 by December. U.S. Homeland Security Investigations agents tracked the construction of the house via wiretaps in October and November.Calexico is a city of about 40,000 people located 120 miles east of San Diego. Two men were arrested Wednesday in Calexico and charged drug trafficking crimes: one at the tunnel house and another at a house believed to have been used to store drugs. Mexico’s Sinaloa cartel has long controlled drug trafficking along the border in California’s Imperial Valley and was under control of Joaquin “El Chapo” Guzman. The investigation led to the confiscation of more than a ton of marijuana. Tunnels hundreds of feet long, some with ventilation and lighting, have been found scattered around the region but not at Calexico until now.