But during its first weeks, asylum seekers and human rights advocates say, migrants have been put on planes without being told where they were headed, and left here without being given basic instruction about what to do next.

When the migrants land in Guatemala City, they receive little information about what it means to apply for asylum in one of the hemisphere’s poorest countries. Those who don’t immediately apply are told to leave the country in 72 hours. The form is labeled “Voluntary Return.”

“In the U.S., the agents told us our cases would be transferred, but they didn’t say where. Then they lined us up to get on the plane,” said Marta, 43, from Honduras. She sat in a migrant shelter here with her 17-year-old son, who nursed a gunshot wound in his left cheek — the work, mother and son say, of a Honduran faction of the MS-13 gang.