New Delhi, July 23 -- Despite a judge's order calling for his return to the United States from El Salvador, a Venezuelan migrant was instead sent back to his home country in a prisoner exchange deal reached last week, an unexpected development that left his lawyers scrambling to locate him.

It marks the latest wrinkle in yet another messy court battle over the Trump administration's crackdown on illegal immigration, which has repeatedly challenged the power of federal courts.

Attorneys for the Venezuelan native - identified only as Cristian in court papers - said during a court hearing Tuesday that they don't know where he is or how to get in touch with him.

After he was deported to a Salvadoran mega-prison in March, U.S. District Judg...