TAPACHULA, Mexico — Elid Turcios sees only dangerous — potentially disastrous — options for his family. They cannot return to Honduras, where he says gang members murdered his parents, nor do they feel safe in Mexico.

But he has heard that ahead lies the new threat that the United States will prosecute him and his wife. “My son and wife are the only thing I have,” Mr. Turcios said gloomily on Wednesday.

Even so, the question is not whether to forge ahead and enter the United States, he said, but how best to do it.

“I want to get to the border,” he said. “Because what else can we do?”

As the Trump administration’s “zero tolerance” policy for illegal entry to the United States dominates debate in Washington and draws international attention and condemnation, it is also sowing turmoil and confusion on the long migrant trail through Central America and Mexico. Word has spread among the migrants — by word of mouth, social media and the snippets of news coverage people are able to collect along the way — that the end of the road could be profoundly different for this wave than for many who went before them.