Complex sentence: One of the most direct and significant outcomes of the Apalachin Meeting was that it helped to confirm the existence of the American Mafia to the public, a fact that some, including Federal Bureau of Investigation Director J. Edgar Hoover, had long refused to acknowledge publicly.
Split into simpler sentences: One of the most direct and significant outcomes of the Apalachin Meeting was that it helped to confirm the existence of the American Mafia to the public. Some, including Federal Bureau of Investigation Director J. Edgar Hoover, had long refused to acknowledge publicly.