The photographer André Cypriano went searching for the same answers some years ago, spending 30 days and nights in the slum, capturing its essence in black and white. Mr. Cypriano wound up there as a guest of Rocinha’s notorious drug lord at the time, Luciano Barbosa dos Santos, who went by the affable nickname Lulu. He had met some of Lulu’s associates while photographing some of the inmates at Ilha Grande prison, Brazil’s equivalent of Alcatraz, and they suggested Rocinha as the setting for a future project.