Mohamedou Ould Slahi Houbeini (* 1970), an internationally renowned author, travelled to Afghanistan in 1990 to help the mujahideen. He underwent training in an al-Qaeda camp and swore an oath of allegiance in 1991. He soon left for Germany but returned to Afghanistan for two months in early 1992 and severed all ties with al-Qaeda after leaving again. However, the United States government claims that Slahi was a recruiter for al-Qaeda and supported it in other ways. In late 1999 and early 2000, he lived in Montreal, Canada, where he was being investigated by the Canadian Secret Service on suspicions of involvement in a terrorist attack. Slahi returned to Mauritania, where he was interrogated and cleared of the accusations. In 2001, he was arrested at home, investigated by the FBI, and then transferred by the CIA to Jordan, where he was tortured. From 2002, he was held without charge at the Guantánamo Bay prison in Cuba for fourteen years. After he was released in 2016, he returned to Mauritania.
Slahi wrote about his experiences in the memoir Guantánamo Diary. In 2022, he received the Dutch PAX Peace Prize (Verededuif) and in September 2023, the Swiss Marco Borradori Lugao Prize.