A guard tower stands at the entrance of the US prison at Guantanamo Bay, also known as "Gitmo," on October 23, 2016 at the U.S. Naval Station at Guantanamo Bay, Cuba.
CNN  — 

A Moroccan man held in Guantánamo Bay for nearly 20 years has been transferred from the US detention facility to his native country of Morocco, the Department of Defense announced Monday, in what is believed to be the first transfer of a detainee in the Biden administration.

A review board in 2016 “determined that law of war detention of Abdul Latif Nasir no longer remained necessary to protect against a continuing significant threat to the national security of the United States” and recommended that Nasir be repatriated to his home country. The steps to repatriate him began in the Obama administration but stalled in the Trump administration.

“The United States commends the Kingdom of Morocco for its long-time partnership in securing both countries’ national security interests. The United States is also extremely grateful for the Kingdom’s willingness to support ongoing U.S. efforts to close the Guantanamo Bay Detention Facility,” the statement said.

On June 17, the Department of Defense notified Congress of its intent to repatriate Nasir, a senior administration official told reporters Monday. The official was unable to say whether Nasir’s repatriation represents an acceleration in US efforts to repatriate Guantanamo detainees but said the administration is committed to a “deliberate” process to reduce the number held at the facility.

There are 39 detainees remaining in Guantánamo Bay, with 10 eligible for transfer who have already been approved by the Periodic Review Board (PRB), 17 eligible for the PRB, 10 involved in the military commission process and two have been convicted, according to a second senior administration official.

Morocco’s public prosecutor announced later Monday that they will investigate Nasir for suspicion of terrorist activity when he arrives to the country, saying in a statement that “based on the results of the investigation, the legal effects will transpire on the person, in absolute respect for the law.”

It was not immediately clear whether he would be detained or released in Morocco, with the US officials referring reporters to the government of Morocco for more information.

The PRB includes a cross-section of representatives from the national security community, with each panel consisting of one senior career official from each of the Departments of Defense, Homeland Security, Justice and State, the Joint Chiefs of Staff and the Office of the Director of National Intelligence, the second official said.

The PRB process reviews assessments of the detainee from the detainee, family members, and personal representatives and personal counsel, plus medical information, an assessment of the condition in the detainee’s home country, plus testimony at the hearing if the detainee chooses to participate, that official also explained.

In February, the Biden administration said it intends to close the Guantánamo Bay detention facility, which was opened in 2002.

The facility was meant to be a place where suspects in the war on terror could be interrogated. But prisoners have been indefinitely detained, many without charges or trial and subjected to reported abuse. As the US war on terror dragged on, the detention facility became an international symbol of US rights abuses in the post-9/11 era.

Former President Barack Obama made a campaign promise in 2008 to close the facility by the end of his administration, which was never realized. Former President Donald Trump signed an executive order in 2018 to keep the facility open.

This story has been updated with additional details.

CNN’s Devan Cole, Chandelis Duster, Ellie Kaufman and Mostafa Salem contributed to this report.