Asadullah Haroon al Afghani, who was detained around age of 25, was never charged with any war crimes and held without a trial.
An Afghan prisoner held in US custody for nearly 15 years has been released from the Guantanamo Bay detention centre after a federal court ruled that he was unlawfully detained, the US Department of Defence has said.
The Pentagon announced on Friday the transfer of Asadullah Haroon al Afghani from Guantanamo Bay prison in Cuba to Afghanistan, after the US District Court of Columbia's ruling that there was no legal basis to justify his continued detention.
Al Afghani, also known as Gul, was not charged with any war crimes and held without a trial.
"Previously, on October 7, 2021 the Periodic Review Board (PRB), a body comprised of senior career officials from the Departments of Defence, State, Justice, and Homeland Security; and the offices of the Director of National Intelligence and the Chairman of the Joint Chiefs of Staff; determined Mr Gul to be eligible for transfer," said Pentagon in a statement.
"The United States thanks the Government of Qatar for its assistance in this matter," it added.
The infamous detention facility opened under former president George W Bush in January 2002 after the 9/11 terror attacks.
The secretive prison once housed hundreds of suspects captured by US forces, many held without charge or the legal power to challenge their detention.
US authorities faced accusations of torture and abuse against prisoners at the facility, with some allegedly held in cages and subjected to illegal interrogation techniques.
The latest transfer from Guantanamo Bay reduces the number of detainees to 36.
"The charges against him were false and the release has proved that he was innocent, but who will return those years of his life?" said Gul's brother Roman Khan from Peshawar in Pakistan, where the family live as refugees.
He said they were informed early Friday of Haroon's freedom.
"It's like Eid in our house, like a wedding. These are very emotional moments for us," Khan said.
Gul, believed to be aged around 40, flew to Qatar after being set free. From there, he is expected to travel to Afghanistan. He was arrested by US forces in 2006 while working as a honey trader travelling between Pakistan and Afghanistan.