President Obama’s promise to close Guantanamo Bay sounded terribly hollow during his State of the Union address on Tuesday night, six years after he first pledged to shut down the military detention center.

One of those who has waited most desperately to discover the camp’s fate was the mother of Mohamedou Ould Slahi, a detainee, who was taken from the sandy streets outside their home in Mauritania on November 20, 2001. As he was led away for questioning, he said: "Don't worry mom, I'll be back soon."

He has been charged with no crime, but Slahi never returned. He remains locked inside the notorious naval base on Cuba’s east coast despite a 2010 judicial ruling that he should be released.

If Obama were inclined to apologize for his failure to shut the facility, it would be too late for Slahi’s mother. She died in 2013.

Thanks to a handwritten diary penned by her son, she lived long enough to read a breathless and heart-rending account of the sexual violence, psychological abuse, savage beatings, and outright torture suffered by her boy.

After a six-year dispute with the U.S. government, his powerful words were published in London on the very day Obama re-made his tired old pledge.

The Guantanamo Diary is heavily redacted but for the first time a detainee’s story has been told publicly by a captive still held inside the camp. The book is a shocking first-hand account of what happened when former Secretary of Defense Donald Rumsfeld personally designated you as a candidate for America’s "special interrogation techniques."

In between the beatings, the threats against his mother, the staged kidnappings, forced-feeding and exposure to extreme cold, Slahi says he was sexually assaulted by female interrogators at the base. Some of the details are redacted, but the attempt to humiliate a man, who considers himself a strict adherent to the teaching of Islam, is clear enough:

“Today, we're gonna teach you about great American sex. Get up!” he wrote. “The two _______ took off their blouses, and started to talk all kind of dirty stuff you can imagine, which I minded less. What hurt me most was them forcing me to take part in a sexual threesome in the most degrading manner. What many _______ don’t realize is that men get hurt the same as women if they’re forced to have sex, maybe more due to the traditional position of the man."

He tried to recite prayers while the women molested him. "Stop the fuck praying! You're having sex with American _______ and you're praying? What a hypocrite you are!" said ______________ angrily, entering the room,” he wrote. “I refused to stop speaking my prayers, and after that, I was forbidden to perform my ritual prayers for about one year to come.”

He claimed one of the women told him: “If you start to cooperate, I’m gonna stop harassing you. Otherwise I’ll be doing the same with you and worse every day... Having sex with somebody is not considered torture.”

Most of Slahi’s torment was far more traditional:

“I have never felt as violated in myself as I had since the DoD team started to torture me to get me admit to things I haven't done…”

“Humiliation, sexual harassment, fear and starvation was the order of the day until around 10 p.m. Interrogators made sure that I had no clue about the time, but nobody is perfect; their watches always revealed it. I would be using this mistake later, when they put me in dark isolation.”

"I'm gonna send you to your cell now, and tomorrow you'll experience even worse."

The U.S. did try to prosecute Slahi, who was named by another Guantanamo detainee as an accessory to 9/11, but their efforts were thwarted by American legal professionals who argued that no fair case could be made. Lt. Col. Stuart Couch, a veteran Marine Corp prosecutor who had lost a close friend during the attack on the World Trade Center, was appointed to bring the case against Slahi.

After nine months’ work, he announced that he could not continue because all of the incriminating evidence against Slahi had been extracted through torture. A U.S. District court judge later agreed with that assessment.

Slahi explains in his diaries that eventually he realized his stay at Guantanamo would be far more pleasant if he told his interrogators what they wanted to hear.

“They dedicated the whole time until around Nov.10, 2003 to questioning me about Canada and Sept. 11; they didn't ask me a single question about Germany, where I really had the center of gravity of my life,” he said. “Whenever they asked me about somebody in Canada I had some incriminating information about that person, even if I didn't know him. Whenever I thought about the words, ‘I don't know,’ I got nauseous, because I remembered the words of ______________, ‘All you have to say is, ‘I don't know, I don't remember, and we'll fuck you!’ Or __________ ‘We don't want to hear your denials anymore!’

And so I erased these words from my dictionary.”