The al-Qaeda recruiter reputed to have assembled the so-called Hamburg Cell, which planned and largely carried out the 9/11 attacks on New York and Washington, has been set free in a prisoner exchange between rebel and regime forces in Syria.

A naturalized German citizen of Syrian origin, Mohammed Haydar Zammar left Germany shortly after the attacks and traveled to Morocco, where he was reportedly seized by the CIA and then “rendered” to Syria. According to local Syrian sources, his release and that of five other “political prisoners” was secured by the Syrian rebel group Ahrar al-Sham in exchange for the release of Syrian army officers. Zammar was serving a 12-year prison sentence in Aleppo’s central prison at the time.

Contacted by the German public broadcaster NDR and Die Süddeutsche Zeitung, family members still living in Germany have confirmed that Zammar was released in a prisoner exchange last fall. Reports published by local Syrian media in late September 2013 include Zammar’s name in a list of the “political prisoners” freed in exchange for the officers.

A native of Aleppo, Zammar moved to Germany with his family as a child and became a German citizen in 1982. By the late 1990s, he was running what the German media has ironically described as a “travel agency” in Hamburg, making arrangements for would-be jihadists to travel to al-Qaeda training camps in Afghanistan. According to a German intelligence report cited in the German press, in 1996 Zammar himself visited an al-Qaeda camp in Afghanistan on the personal invitation of Osama bin Laden. He is supposed to have made the trip many times thereafter.