The routes that migrants travel are well known -- to Mexican authorities, criminals, and local people. Operativos, the mobile Mexican military units based along the route, sometimes stages night ambushes on trains. Terrified of being sent back home, migrants often jump from moving trains. The operativos send dogs to find them.
Kidnappers are another group that preys on migrants, taking advantage of the confusion of small towns along the route, where the trains stop. Most migrants have a "backer" in either the United States or Central America who helps pay for their trip. (An entire journey can cost as much as $8,000, Jácome estimates.) "They say [to the migrants,] give me the phone number" of the backer, Jácome recounts from interviews with kidnapping victims. Even if the ransoms they collect are small, say 2,000 pesos (about $150), the volume makes up for it: On a good day, kidnappers could make thousands of dollars.