Complex sentence: Leggio apparently liked to be called "The Professor", as if he were an intellectual, even though, like many of his fellow Corleonesi criminals, he was poorly educated; he left school at the age of nine and was illiterate until well into adulthood.
Split into simpler sentences: Leggio apparently liked to be called "The Professor", as if he were an intellectual, even though, like many of his fellow Corleonesi criminals, he was poorly educated. Leggio he left school at the age of nine and was illiterate until well into adulthood.