The 12-page document stems from March 2008. Anyone who reads it is left with the impression that the prisoner that the report describes is a major player in international terrorism.

According to the first page of the document, which is one of over 700 Guantanamo detainee assessments  obtained by WikiLeaks, the prisoner confessed to being a member of al-Qaida and attending its training camp in Afghanistan. The man, who was given the detainee number US9MR-000760DP, allegedly swore "bayat" (an oath of allegiance) to al-Qaida leader Osama bin Laden and was willing to die as a martyr for bin Laden's cause. He also allegedly stated that his main responsibility had been to recruit volunteers for the terrorist organization in Europe.

In addition, the Joint Task Force claims in its assessment that the prisoner ran "the al-Qaida cell in Duisburg, Germany." This important piece of information is stated as fact in the file, without any ifs, ands or buts.

However, German investigators were -- and still are -- unaware of the existence of any Duisburg cell. Nor is any such cell mentioned in the files resulting from the extensive investigations conducted after the Sept. 11 attacks.

A Decade of Terrorism

Prisoner number US9MR-000760DP is a Mauritanian, Mohamedou Ould Slahi, born in Rosso in southwestern Mauritania in 1970. He came to Germany in 1988 on a scholarship with the Carl Duisberg Society. He attended university in the western city of Duisburg, where he earned an engineering degree. After the attacks of Sept. 11, 2001, Slahi was arrested in Mauritania and sent to Jordan, where he was detained for several months. In August 2002, he was transferred to Guantanamo, where he has been incarcerated ever since.

Slahi's story is relatively easy to reconstruct. His case exemplifies the years before and after 9/11. His life almost completely documents a decade of terrorism against the West -- as well as the difficulties it faced in finding a suitable response to this terrorism. SPIEGEL already devoted an extensive story  to the Slahi case in 2008, when it spoke with his relatives in Mauritania, his attorneys, the military prosecutor to whom his case was assigned and the man who interrogated him at Guantanamo.

All of this makes it all the more interesting to compare the previously known facts about the Mauritanian with the memorandum that has now become available, the "detainee assessment" by the Joint Task Force. It doesn't take long to reach the conclusion that the two things have nothing in common.

Campaigned for Global Jihad

The document from Guantanamo describes a different Slahi, a dangerous and unscrupulous terrorist prepared to do anything. It outlines a career within al-Qaida, a career for which neither German nor international investigators ever found sufficient proof. But the military interrogators at Guantanamo apparently did.

A person who is only familiar with the secret dossier on prisoner number US9MR-000760DP is forced to conclude that the detainee must be a key figure in international terrorism, a man with close ties to the top hierarchy of the terrorist organization. According to the dossier, he was not only the head of the "al-Qaida cell" in Duisburg, but also the leader of the cell that once planned to blow up Los Angeles International Airport, a plan referred to in the file as the "Millennium bombing" plot. In addition, the first page of the file states that Slahi recruited three of the Sept. 11 hijackers into al-Qaida.

German investigators were always more cautious in their assessment. They say that the statement that Slahi recruited some of the 9/11 attackers is nothing but a myth, and that they have no information of their own to support such a claim. A federal court in the United States, which reviewed the Slahi case last year, also concluded that the prisoner should be released because there was no justification for keeping him at Guantanamo any longer.

It is a fact that Slahi campaigned for global jihad. In the 1990s, he preached in dreary backyard mosques in Duisburg and nearby Krefeld. The Office for the Protection of the Constitution, Germany's domestic intelligence agency, opened a file on him at the time. The Mauritanian was suspected of having sent "al-Qaida-related funds" to a man in Sudan through a business account. But the Office for the Protection of the Constitution was never able to confirm this suspicion.

Direct Approval from the Pentagon

A photo taken in his student days in Duisburg shows Slahi as a young man with a narrow face, dark hair and a moustache. But the image on the cover page of his "detainee assessment" looks completely different, showing a much stockier, bald man with a thin, black beard.

There are long passages in the document that contain the prisoner's "own account," although the document also notes that these statements are recorded without having been checked for accuracy or reliability. The same caveat should probably be applied to most of the 12 pages in the file.

There is not a word in the Guantanamo document about the conditions under which Slahi's extensive statements came about. In fact, only three words, "enhanced interrogation methods," or even one word, "torture," would have been sufficient. It is a verifiable fact that Slahi was tortured at Guantanamo because the approval came directly from the Pentagon.

Taken Out to Sea

When two agents with the BND, Germany's foreign intelligence service, and an agent from the Office for the Protection of the Constitution went to Guantanamo to question Slahi in September 2002, shortly after he was transferred there, they gave up in frustration after 90 minutes. The prisoner, according to their report, said "nothing that we didn't already know."

More than half a year later, in May 2003, American intelligence agents also questioned the Mauritanian. They used sleep deprivation and constant exposure to loud noise in an effort to get him to talk. On another occasion, they showed him a letter stating that his mother might be sent to Guantanamo because her son wasn't cooperating sufficiently. Finally, in August 2003, then Defense Secretary Donald Rumsfeld approved the use of enhanced interrogation methods on the recalcitrant detainee, who was refusing to talk. At that point, everyone still believed that Slahi was a key al-Qaida figure.

About two weeks after Rumsfeld had approved enhanced interrogation, soldiers blindfolded the prisoner and took him out to sea on a boat so that he would believe that he was about to be executed.

Soon afterwards, the Mauritanian capitulated and began to talk -- effusively, in fact. In light of his extensive statements, he was "one of the most valuable sources" at Guantanamo, the March 2008 assessment of Slahi concluded. "He has been highly cooperative," it said, "and continues to provide valuable intelligence."

Devastating Ruling

In November 2006, Slahi himself wrote: "I yes-ed (sic) every accusation my interrogators made."

But there was one charge he apparently continued to deny, namely, that he had recruited and brought to Afghanistan Mohamed Atta and other 9/11 attackers. This suspicion stemmed from a statement made by 9/11 mastermind Ramzi Binalshibh, one of the 14 "high value" detainees in Guantanamo.

In addition to Slahi's status as a supposedly "high risk" prisoner, the assessment lists about 20 issues for which the United States hoped Slahi could provide further information.

The document does not mention that then-US military prosecutor Stuart Couch resigned from the case because, after reviewing it, he concluded that his country had acted incorrectly. According to Couch, the United States was also obligated to consider evidence that could exonerate the defendant.

Almost exactly one year ago, a US federal judge issued an initial verdict on the Slahi case. It is a devastating ruling that declares the previously classified and now published "detainee assessments" and the evidence they contain to be null and void.

Germany Is Destination of Choice

According to the judge, the US authorities were apparently unable to prove that Slahi was truly a member of al-Qaida at the time of his capture or that he had supported the terrorist organization in any form. In fact, the judge argued, there was no evidence to support such a claim.

The US government filed an appeal against the federal court's decision. Slahi's attorney, Nancy Hollander, continues to demand his immediate release. "After almost 10 years, the government has not been able to meet the minimal burden to detain him that's required under habeas (corpus)," Hollander said in March 2010. "He should be free."