TORONTO - Luther Samuel, the man authorities say sold fraudulent school papers allowing members of a possible al-Qaeda sleeper cell to take root in Canada, long felt a duty to bring career training to the city's black community. When he purchased the Ottawa Business College, a private vocational school, in 1997, he quickly moved it from a downtown Ottawa address to a low-rent stretch of Scarborough to be close to the black and ethnic neighbourhoods he knew, former associates said. Within two years, however, his school had degenerated into a mere diploma mill, selling fraudulent documents and allowing 400 foreign...