Story highlights Mohamedou Slahi's harrowing story is the first time a serving Gitmo inmate has been published

He describes beatings, sensory deprivation and starvation

He was originally detained in 2002, accused of recruiting 9/11 hijackers

His lawyers say there is very little evidence against him

London (CNN) Mohamedou Slahi was wearing black-out goggles. A guard dragged him onto a boat and someone forced him to drink seawater.

"It was so nasty I threw up...They stuffed the air between my clothes and me with ice cubes from my neck to my ankles...every once in a while one of the guards smashed me, most of the time in the face."

In a new book Guantánamo Diary, Slahi paints a horrifying picture of life at the hands of interrogators in the notorious U.S. military prison in Cuba. The book depicts long days in isolation, sometimes chained to the floor in agonizing positions, held in extreme temperatures, often deprived of food and sleep. On multiple occasions he describes being beaten and humiliated by his questioners. He says he was left "shaking like a Parkinson's patient" and felt one of his interrogators "was literally executing me but in a slow way."

The 44-year-old electrical engineer, originally from Mauritania, has been held in Guantánamo Bay since 2002. He was accused of being a member of al Qaeda and of recruiting three of the hijackers in the 9/11 terrorist attacks, as well as being involved in other terror plots in Canada and the United States. He's never been charged and his lawyers say there is very little evidence against him.

Slahi admits to traveling to Afghanistan to fight in the early 1990s, when the U.S. was supporting the mujahedeen in their fight against the Soviet Union. He pledged allegiance to al Qaeda in 1991 but claims he broke ties with the group shortly after.

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