Daniel Shea, grew up in a poor neighborhood in The Bronx. He always idolized his older brother, James and was always near him. His father Mickey was a bootlegger and bar owner, and they became rich working with Vito Corleone. By the early 1950s, he became the Assistant District Attorney in New York under Senator Davis. Although he was married to a woman named Jeannie, Danny and his brother were both notorious womanizers and philanderers.
By 1956, his father made a deal with Tom Hagen to get his son, James K. Shea, elected President in 1960, with the belief he would not attempt to prosecute any Mafia families during his tenure. Danny worked very hard on his brother's campaign, and in 1960, he was made his brother's Attorney general when he was elected president, making him the youngest Attorney general in American history.
He became involved in key moments in American history, like the attempted assassination of Fidel Castro in Cuba, the Cuban Missile Crisis, the killing of CIA assassin, Carmine Marino, and the prosecution of Mafia Don's, such as Carlo Tramonti, of New Orleans. It was his attempted prosecution and deportation of Tramonti that created a personal vendetta that would eventually end in his brother, James being assassinated.
After the assassination
It was in 1964 that his brother was assassinated and Danny realized whose fault it was, after angering the wrong people. After that he was advised to step down as Attorney general. He then ran, with the Corleone family's backing, for a vacant Senate seat in New Jersey in 1966, which he won easily.