Our sources told us about despair and hope among an exploding homeless population of undocumented immigrants waiting to return to the U.S. illegally. They are deported to Tijuana, and live along the banks of the Tijuana River. Thousands of people making homes in underground bunkers, inside storm drains and in makeshift tree houses in a quest to return to their families across the border.
Our sources also told us about an elaborate yet dangerous drug tunnel connecting San Diego to Tijuana. The Mexican military gave us extraordinary access -- and we went down the tunnel to experience the dark, cramped area with little air, where workers shoveled out piles of earth.
We set out to witness what our neighbors endure across the border, so we could tell their stories, which eventually were picked up for viewing by CNN and ABC affiliates nationwide.