In a blow to the Trump administration, a federal judge ruled Friday the U.S. government acted illegally when it mistakenly deported a Maryland father to El Salvador and ordered that he must be returned to the United States.

“This was an illegal act,” U.S. District Judge Paula Xinis of Maryland said of the deportation of Kilmar Abrego Garcia.

Xinis gave the administration until 11:59 p.m. Monday to remove Abrego Garcia from the violent El Salvador prison where he is being held and return him to U.S. soil.

Abrego Garcia, 29, was among the hundreds of alleged members of crime gangs MS-13 and Venezuela’s Tren de Aragua the government expelled from the U.S. to El Salvador last month.