A Maryland man who had been granted legal protection from deportation is now being held in a notorious Salvadoran prison after U.S. Immigration and Customs Enforcement (ICE) mistakenly deported him due to what officials are calling an “administrative error.”

Kilmer Armado Abrego-Garcia, who has a U.S. citizen wife and a 5-year-old child, is currently incarcerated at CECOT, a maximum-security prison in El Salvador known for its harsh conditions. In a sworn court filing on Monday, ICE acknowledged the mistake, admitting Abrego-Garcia was removed from the U.S. despite an immigration judge’s prior ruling that he could not be deported to El Salvador due to the risk he faced there.

The error came to light as part of a lawsuit filed by Abrego-Garcia’s attorneys, who are seeking his immediate return to the United States. The attorneys argue that their client was unlawfully removed and is now in grave danger.

In response, the U.S. government conceded the deportation was a mistake but claimed that, because Abrego-Garcia is no longer in U.S. custody, the court does not have the authority to compel his return or to require the government of El Salvador to release him.

Abrego-Garcia had previously applied for asylum and was found removable, but an immigration judge ultimately granted him “withholding of removal” — a legal protection that prohibits deportation to a country where the individual is likely to face persecution or torture. That protection was based in part on allegations that a confidential informant had once linked him to MS-13, a claim he disputes.

Despite that ruling, ICE detained Abrego-Garcia earlier this month, reportedly telling him his status had changed. He was transferred to a Texas detention facility and then put on a deportation flight to El Salvador on March 15.

“Abrego-Garcia…was on the third flight and thus had his removal order to El Salvador executed,” wrote Robert L. Cerna, ICE’s acting field office director, in a declaration submitted to the court. “This removal was an error.”

The case has sparked outcry from immigration advocates and legal experts, who say it raises serious concerns about oversight and accountability within the U.S. immigration system.