From USA TODAY.

The Supreme Court has temporarily blocked a federal judge’s order to return Kilmar Armando Abrego Garcia, 29, to the U.S. He was deported by "an administrative error" to his native El Salvador and sent to the country’s most notorious prison on March 15.

U.S. District Judge Paula Xinis of Maryland said Abrego Garcia’s deportation was "an illegal act" and ordered the return of Abrego Garcia on April 4. The Trump administration appealed the order, but the U.S. Court of Appeals for the Fourth Circuit denied it.

The Justice Department asked the Supreme Court on Monday to halt the return. Chief Justice John Roberts issued the stay.

President Donald Trump’s administration has acknowledged the mistake. However, it says Abrego Garcia can’t be returned to the U.S. because he’s in Salvadoran custody. U.S. courts have no jurisdiction there, though the U.S. is paying the El Salvadoran government $6 million to house deportees from the U.S