Mohamedou Ould Slahi, the author of a New York Times best-selling memoir about his detention and torture at the Guantanamo Bay facility, was recently repatriated to his native Mauritania in West Africa, the Defense Department announced Monday.

Slahi, who had been held without charge or trial since August 2002, is the highest-profile transfer out of the U.S. detention center since U.K. citizen Shaker Aamer was repatriated one year ago. There are now 60 captives remaining at Guantanamo.

In a statement from the ACLU, which championed Slahi’s release, the former detainee was quoted as saying, “I feel grateful and indebted to the people who have stood by me. I have come to learn that goodness is transnational, trans-cultural, and trans-ethnic. I’m thrilled to reunite with my family.”

Nancy Hollander, one of Mohamedou Ould Slahi’s attorneys, said in a statement that Slahi “wants nothing more than to be with his family and rebuild his life.”

“We are thrilled that our client’s nightmare is finally ending,” she said.

Slahi traveled to Afghanistan in the 1990s, joined up with mujahedeen who were fighting a civil war against the Soviet-backed government, and swore allegiance to al-Qaeda. The U.S. government accused him of being one of the planners of a failed plot to blow up Los Angeles International Airport in 1999 known as the Millennium Bombing. The U.S. also accused him of playing a role in the 9/11 attacks.

But U.S. District Court Judge James Robertson said the government’s evidence against Slahi was thin and granted his petition for habeas corpus in March 2010, ordering him to be released. Robertson said Slahi “may very well have been an al-Qaeda sympathizer, and the evidence does show that he provided some support to al-Qaeda, or to people he knew to be al-Qaeda.”

But “such support was sporadic… and, at the time of his capture, nonexistent.” The Obama administration appealed the judge’s decision, and Slahi’s case languished in federal court for six years.

Last July, he was granted a parole board hearing at Guantanamo to determine whether he still posed a threat to national security and if he could be released. The board, made up of officials from the departments of Defense, Homeland Security, Justice, and State; the Joint Chiefs of Staff; and the Office of the Director of National Intelligence “determined continued law of war detention of Slahi does not remain necessary to protect against a continuing significant threat to the security of the United States.”

“As a result of that review, which examined a number of factors, including security issues, Slahi was recommended for transfer,” the Defense Department said in a statement Monday, which noted that Slahi’s release was part of a larger effort by the Obama administration to shutter Guantanamo before Obama leaves office. “The United States coordinated with the government of Mauritania to ensure this transfer took place consistent with appropriate security and humane treatment measures.”

Slahi turned informant in 2003 and was rewarded with special privileges that included access to a refrigerator and a fenced-in compound at Guantanamo, separated from other detainees, where he could garden, paint, and write.

But his life at Guantanamo had been far worse before then. His 2015 book, “Guantanamo Diary” — portions of which were heavily redacted by the government — recounts in vivid and harrowing detail the Mauritanian’s rendition, his torture by interrogators, and the grave conditions of his confinement.

“‘Blindfold the motherfucker if he tries to look…’ One of them hit me hard across the face, and quickly put the goggles on my eyes, ear muffs on my ears, and a small bag over my head. I couldn’t tell who did what. They tightened the chains around my ankles and my wrists; afterwards, I started to bleed. All I could hear was [redacted] cursing, ‘F-this and F-that!’ I didn’t say a word, I was overwhelmingly surprised, I thought they were going to execute me,” Slahi wrote about the “special interrogation” plan that took place at Guantanamo in August 2003, which was personally approved by then–Secretary of Defense Donald Rumsfeld.

According to internal government documents, the plan called for interrogators to take Slahi onto a boat and lead him to believe he was going to be executed.

“Thanks to the beating, I wasn’t able to stand, so [redacted] and the other guard dragged me out with my toes tracing the way and threw me in a truck, which immediately took off,” Slahi wrote. “The beating party would go on for the next three or four hours before they turned me over to another team that was going to use different torture techniques.”

Turning Slahi’s handwritten diary into a published book was no easy feat. His own words were once considered classified, and the government argued that if what he wrote was publicly released, it would threaten national security. His lawyers sued the government in 2006 and won that legal battle six years later.