In this year-long investigation from Futuro Investigates, we dig into how the Border Patrol’s decades-long deterrence policies create a deadly funnel, pushing migrants to cross through the Sonora Desert in southern Arizona—one of the deadliest terrains in the country. More than 4,000 remains have been recovered, and many have disappeared here. While the actual death toll is unknown, experts say it is likely much higher. As a result, volunteer organizations go to the most dangerous areas to search for missing people. We question why volunteers have to take on this work, and how this crisis fuels the Border Patrol’s budget.