Who is the main subject in the nonfiction book, The Irishman?

Frank “The Irishman” Sheeran is the book's main subject. He was an American citizen of Irish and Swedish descent. He served time in the United States Army before getting involved with the mafia. Sheeran was a trusted member of this group before he even realized that they were criminals. Through his life of crime, Sheeran claims that he delivered weapons for use by the Cubans in the Bay of Pigs Invasion and worked as a hitman for both Bufalino and Hoffa. Sheeran also claims to have acted alone when he murdered both Gallo and Hoffa. However, Brand suggests none of these stories are supported by facts.