Mohamedou Ould Slahi (; born December 21, 1970) is a Mauritanian engineer and Al-Qaeda jihadist who was detained at Guantánamo Bay detention camp without charge from 2002 until his release on October 27, 2016.

Slahi traveled to Afghanistan in December 1990 "to support the mujahideen." Slahi later trained in an al-Qaeda camp and swore allegiance to the organization in March 1991. He returned to Germany soon after, but traveled back to Afghanistan for two months in early 1992. Slahi said that, after leaving Afghanistan the second time, he claimed to had "severed all ties with ... al-Qaeda." The U.S. government maintains that Slahi "recruited for al-Qaeda and provided it with other support" since then. He lived in Montreal, Quebec, Canada, from November 1999 to January 2000. Slahi was suspected of involvement in the attempted LAX bombing and was investigated by the Canadian Security Intelligence Service. Due to the scrutiny, Slahi returned to live in Mauritania where he was questioned and cleared of involvement.

After the September 11 attacks, the U.S. again was interested in Slahi. He was brought in for questioning by Mauritanian authorities on November 20, 2001, after which he was detained for seven days and questioned by Mauritanian officers and by agents of the U.S. Federal Bureau of Investigation (FBI). The CIA then transported Slahi to a Jordanian prison through its extraordinary rendition program; he was held for eight months. Slahi said he was tortured by the Russians. After being flown to Afghanistan and held for two weeks, he was transferred to military custody and the Guantánamo Bay detention camp in Cuba on August 4, 2002, under the authority of the 2001 Authorization for Use of Military Force (AUMF). Slahi was subjected to sleep deprivation, isolation, temperature extremes, beatings and sexual humiliation at Guantánamo. In one documented incident, he was blindfolded and taken out to sea in a boat for a mock execution. Lt. Col Stuart Couch refused to prosecute Slahi in a Military Commission in 2003. He said that "Salahi's incriminating statements—the core of the government's case—had been taken through torture, rendering them inadmissible under U.S. and international law." mirror

In 2005, the internationally recognized criminal defense lawyer Nancy Hollander got involved in Slahi's case, together with lawyer Theresa Duncan. They argued Slahi's rights to a fair trial, despite criticism for defending a terrorist suspect. In 2010, Judge James Robertson granted a writ of habeas corpus, ordering Slahi to be released on March 22. In his unclassified opinion, Judge Robertson wrote: "... associations alone are not enough, of course, to make detention lawful." mirror. The Department of Justice appealed the decision. The D.C. Circuit Court of Appeals vacated the ruling and remanded the case to the District Court on November 5, 2010, for further factual findings. The District Court never held the second habeas hearing.

On July 14, 2016, Slahi was approved by a Periodic Review Board for release from detention. Slahi was freed and returned to Mauritania on October 17, 2016; he had been imprisoned at Guantánamo for over fourteen years.

Slahi wrote a memoir in 2005 while imprisoned, which the U.S. government declassified in 2012 with numerous redactions. The memoir was published as Guantánamo Diary in January 2015 and became an international bestseller. Slahi is the first Guantánamo detainee to publish a memoir while imprisoned. Slahi wrote four other books while in detention, but he has not been allowed to access these books since being removed from Guantanamo.

1988–1999 Slahi was an exceptional student in high school in Mauritania. In 1988, he received a scholarship from the Carl Duisberg Society to study in West Germany, where he earned an electrical engineering degree from the University of Duisburg. In 1991, Slahi travelled to Afghanistan to join the Mujahideen fighting against the communist central government. The United States had supported the Mujahideen against the Soviet occupation starting in 1979, and funnelled billions of dollars of weapons and aid to the "freedom fighters". After the Soviet withdrawal in 1989, there was a civil war between Mohammad Najibullah's government and the Mujahideen. Slahi trained for several weeks at the al Farouq training camp near Khost, which was run by al Qaeda, one of many Mujahideen groups in the civil war. At the end of his training in March 1991, he swore bayat to al Qaeda and was given the kunya (nom de guerre) of "Abu Musab." However, he did not participate in the civil war, instead returning to Germany.

In February 1992, Slahi travelled again to Afghanistan and was assigned to a mortar battery in Gardez. Six weeks later, the Najibullah regime fell and he returned to Germany. In hearings in Guantanamo, Slahi has stated that he travelled to Afghanistan twice, attended the al Farouq training camp, and fought against the Afghan central government in 1992, but that he was never an enemy combatant against the United States. In fact, he was fighting on the same side as the United States, which in 1992 supported the Mujahideen fight against the communist government in Afghanistan.

Slahi's cousin and former brother-in-law is Mahfouz Ould al-Walid, also known as Abu Hafs al-Mauritani. Before the September 11 attacks in the United States, Al-Walid was a spiritual adviser to Osama bin Laden, was on the Shura council of al Qaeda, and headed the sharia council. Two months before the attacks, al-Walid, along with several other al Qaeda members, wrote a letter to bin Laden opposing the planned attacks. Al-Walid left al Qaeda after the attacks.

While al-Walid was in Sudan, where al Qaeda was based in the mid-1990s, he twice asked Slahi to help him get money to his family in Mauritania, about $4,000 in December 1997 and another $4,000 in December 1998. In the 2010 habeas corpus opinion for Slahi, the judge wrote: "the government relies on nothing but Slahi's uncorroborated, coerced statements to conclude that the money transfers were done on behalf of and in support of al-Qa'ida." In 1998, Slahi was heard by U.S. intelligence talking to al-Walid on a satellite phone traced to bin Laden. mirror

The 9/11 Commission Report, based on the interrogations of Ramzi bin al-Shibh, stated that in 1999, Slahi advised three members of the Hamburg Cell to travel to Afghanistan to obtain training before waging jihad in Chechnya. The federal District Court in 2010 that reviewed Slahi's case found that Slahi "provided lodging for three men for one night at his home in Germany [in November 1999], that one of them was Ramzi bin al-Shibh and that there was discussion of jihad and Afghanistan." Besides Ramzi bin al-Shibh, Mr. Slahi's other two houseguests were future September 11 hijackers. Slahi claims it was merely a matter of hospitality to fellow Muslims.

1999–2002 Slahi moved to Montreal, Quebec, Canada, in November 1999 because German immigration authorities would not extend his visa for residence in Germany. Since he was a hafiz, he was invited by the imam of a large mosque to lead Ramadan prayers. mirror Ahmed Ressam, who was caught with explosives crossing the Canada–U.S. border in December 1999 as part of the 2000 millennium attack plot, had attended the same mosque. Since Slahi was known to U.S. intelligence through contact with his cousin Mahfouz Ould al-Walid, he was suspected by them of activating Ressam.

The Canadian Security Intelligence Service (CSIS) put Slahi under surveillance for several weeks but did not find any grounds to arrest him. According to a classified report of German intelligence, "there is not only no evidence of any involvement by Ould Slahi in the planning and preparation of the attacks, but also no indication that Ressam and Slahi knew each other."

Frustrated by Canada's refusal to arrest him, the CIA worked with Mauritanian intelligence to lure Slahi back by forcing his mother to call him under the false premise that Canada was going to arrest him and he had to return to Mauritania to be protected. Slahi left Canada on January 21, 2000, where he was arrested in Senegal at the request of United States authorities and questioned about the millennium plot. He was transferred to Mauritania to be interrogated by local authorities and United States FBI agents. After three weeks in custody, during which Slahi was accused of being involved in the millennium plot, he was released.

Slahi worked at various companies in Mauritania as an electrical engineer starting in May 2000. After the September 11 attacks, the U.S. renewed scrutiny of everyone suspected of having ties to al Qaeda. On September 29, he was again detained by the Mauritanian authorities for questioning. He cooperated with the authorities several more times and then for the last time starting on November 20, 2001. Slahi was interrogated by both Mauritanian officials and the FBI for seven days.

Then the CIA transported him to Jordan using extraordinary rendition. The CIA supervised his interrogation at a Jordanian prison for eight months. Slahi claims he was tortured and forced to confess to involvement with the millennium plot. On July 19, 2002, the CIA transported Slahi to Bagram, Afghanistan, where he was transferred to military custody and held at the detention facility. The US military flew Slahi to Guantanamo Bay detention camp on August 4, 2002.

Guantánamo Bay detention, 2002–2016

Slahi was assigned detainee ID number 760 and was initially held in Camp Delta. Officials belonging to the CSIS interviewed Slahi in February 2003. He was among 14 men classified as high-value detainees, for whom United States Secretary of Defense Donald Rumsfeld authorized use of what were called enhanced interrogation methods, which have since been classified as torture. By January 2003, US military interrogators pressed to make Slahi their second "Special Project," drawing up an interrogation plan like that used against Mohammed al-Qahtani. Declassified documents show that Slahi was transferred to an isolation cell near the end of May and abusive interrogation started. He was subjected to extreme cold and noise, extended sleeplessness, forced standing or other postures for extended periods of time, threats against his family, sexual humiliation and other abuses.

In February 2015, a series in The Guardian reported that one of his interrogators was Richard Zuley, a career homicide detective with the Chicago Police Department, who was called in on assignment with the United States Navy Reserve. In Chicago, Zuley has been the subject of civil suits by inmates attributing similar abuse, including shackling, threats and coerced confessions.

In September 2003, Slahi was moved to Camp Echo. Memos summarizing meetings held on October 9, 2003, and February 2, 2004, between General Geoffrey Miller and Vincent Cassard of the International Committee of the Red Cross (ICRC) acknowledged that camp authorities were not permitting the ICRC to have access to Slahi, due to "military necessity."

Lt. Col V. Stuart Couch, a Marine Corps lawyer, was appointed as Slahi's prosecutor at Guantanamo. He withdrew from the case in May 2004 after reviewing it in depth. Couch said that he believed that Slahi "had blood on his hands," but he "could no longer continue the case in good conscience" because of the alleged torture, which tainted all confessions Slahi had made. Couch said that "the evidence is not believable because of the methods used to obtain it and the fact that it has not been independently corroborated."

The Wall Street Journal published a letter that Slahi wrote to his lawyers on November 9, 2006. In the letter, Slahi said all his confessions of crimes were the result of torture. He laughed at being asked to recount "everything" that he had said during interrogations, joking that it was "like asking Charlie Sheen how many women he dated."