Two years ago, an SUV carrying four men screeched to a halt in front of the house of German Valdivieso Diaz, where he still lives with his parents and two nephews. They demanded to know how to find Valdivieso. And then they threatened to kill him.
When the men left, Valdivieso said his terrified mother called, urging him to stay in Mexico City where he was taking a course—more than 700 kilometers (435 miles) northwest of their rural home in La Ventosa near the Pacific coastline.