Both JFK and RFK conducted affairs with Marilyn Monroe in the early 1960s, which proved to be dangerous, as Marilyn was deeply depressed when the brothers cut all ties with her, fearing that she would expose their affairs, prompting them to make sure that she wouldn’t talk by blackmailing her with compromising pictures taken of her whilst intoxicated during a visit to the Cal-Neva Lodge. If she talked, the pictures would no doubt be on the front page of every newspaper within hours. The following weekend, Marilyn was dead, sparking speculation that the Kennedy brothers either sparked her suicide, or arranged for her death to silence her forever. In her interview with Larry King, Judith Exner said, “I think that Jack was very reckless. He took tremendous chances in many areas, not just with me. But I think that’s the way he was brought up. I think that Jack emulated his father a great deal and in many ways.”

The brothers were taking on the Mob, the CIA, the military and big business. John Kennedy had made it plain that if he won the 1964 presidential race, he would not be running alongside Lyndon Johnson. He was also determined to get rid of and remove J. Edgar Hoover from the FBI. JFK didn’t necessarily dislike Hoover, although he was tailing JFK in order to create a file of evidence to use to blackmail JFK, including his association with Giancana’s girlfriend, Judy Campbell and the various unethical goings on at Frank Sinatra’s private parties. Bobby, on the other hand, had a tense relationship with Hoover, who picked on Bobby for anything and everything whilst making sure that he never found out about the illegal wire taps he had used to collect incriminating information on mob bosses and celebrities.

The Kennedy brothers were seen by some, as immature and at times cruel. This is evident in the dismissal of Frank Sinatra from the Kennedy family. Instead of quietly breaking away from Sinatra, the brothers decided to publically humiliate him by arranging to stay at his Palm Springs home on a tour of the West, and cancelling at the last minute after Sinatra had renovated his home and bragged for months to anybody who would listen that he was accommodating the president, only to stay at the home of Republican and Sinatra rival Bing Crosby. The incident not only caused embarrassment forFrank but also ended the friendship he had with Peter, the Kennedys brother in law, as Frank felt betrayed by Peter.

In their three years of power, the Kennedy brothers had made more enemies than any political partnership in American history. So was it conceivable that the murder of the President of the United States could have originated from the underbelly of America’s society through the intrigue and planning of the Mafia.

Top mob members wanted Robert Kennedy and later John Kennedy murdered. First, they were outraged at what they perceived as the brothers' hypocrisy, and second, they were alarmed at the increasing danger of being further investigated and prosecuted. The hypocrisy they saw derived from their notion that Joseph Kennedy's history with organized crime figures plus some racketeers' support of JFK's election warranted protection from, not their selection for, aggressive prosecution. This compromising history was compounded by the administration's use of mob members in its attempts to deal with Fidel Castro. The U.S. Government personnel plotted to kill Castro from 1960 to 1965. American underworld figures and Cubans hostile to Castro were used in these plots and were provided encouragement and material support by the U.S. They delivered, and they expected appropriate acknowledgment of their cooperation. Rather than laying off, the Justice Department was piling on. Major mob leaders were outraged and planned revenge.