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. Ahmed Ressam, who was caught with explosives crossing the Canada–US 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.