Friends of Yemeni former Guantanamo Bay detainee Emad Hassan have taken to social media to pay tribute to him after he passed away from an illness in Oman on Thursday.
Hassan, 45, spent 13 years jailed at the infamous Camp X-Ray facility at the US military base in Cuba, where he reported being tortured by US soldiers.
"With a heavy heart, I share the news of our brother Emad Hassan's passing. A former #Guantánamo prisoner, teacher, and leader, Emad was one of the best men I have known. He sacrificed years fighting for justice in Guantánamo. May Allah grant him Jannah and bring peace to his loved ones," wrote his fellow former Guantanamo Bay inmate and activist Mansouor Adayfi on X.
Hassan was captured along with 15 men in a raid on a house in Faisalabad, Pakistan in 2002. The men said they were students but were held in detention in Kandahar and later transferred to the Guantanamo Bay detention facility.
At Guantanamo Bay, Hassan was a long-term hunger striker, having started his protest in 2007. In letters written from captivity, Hassan detailed how he had been force-fed by US authorities.
In a tribute posted to X, UK-based NGO CAGE described Hassan as having been a "leader and teacher behind bars".
Hassan's former lawyer also took to X to share memories of working with the former detainee.
"Emad was my first client at Guantanamo. I've told the story often about how I walked in and saw this impossibly thin young man (then on his 5th/6th year of hunger strike) with a bright smile and Coolio-style braids - he said, to make his mother smile on the video calls," lawyer Alka Pradhan wrote.
"Then he suddenly cried, thinking of his mother and whether he'd ever see her again. I didn't know what to do. He'd been snatched as a kid, sold to the U.S. government for bounty, tortured badly in Kandahar and then at Guantanamo. His only method of protest was hunger striking," she continued, adding that his detention and hunger strike was "a testament to the total corruption, racism, and cruelty of U.S. govt's regime at GTMO".
The US first opened the Guantanamo Bay detention centre under President George W. Bush in January 2002 after the 9/11 attacks and the invasion of Afghanistan. It was intended to hold and interrogate prisoners with alleged links to al-Qaeda or the Taliban at the time.
Scores of suspects from multiple countries were later sent to the Cuban facility - often in highly controversial circumstances.
The detention centre became notorious after reports emerged detainees were humiliated and tortured there.
Numbers have dwindled in recent years, after hundreds of former detainees were released and then returned home or re-settled in third country locations.
This week, US prosecutors reached a deal with Guantanamo inmate and 9/11 mastermind Khalid Sheikh Mohammed, reportedly involving a guilty plea in exchange for avoiding a death penalty trial.
The agreements with Mohammed and two other accused moves their long-running cases toward resolution. These have been bogged down in pre-trial maneuveresfor years while the defendants remained held at the Guantanamo Bay military base.