From a biography of Carlos Marcello:


"After becoming president John F. Kennedy appointed his brother, Robert Kennedy, as U.S. Attorney General. The two men worked closely together on a wide variety of issues including the attempt to tackle organized crime. In March 1961, the Attorney General took steps to have Marcello deported to Guatemala (the country Marcello had falsely listed as his birthplace). On 4th April, Marcello was arrested by the authorities and taken forcibly removed to Guatemala.

It did not take Marcello long to get back into the United States. Undercover informants reported that Marcello made several threats against John F. Kennedy, at one time uttering the traditional Sicilian death threat curse, "Take the stone from my shoe." In September 1962 he told private investigator Edward Becker that a dog will continue to bite you if you cut off its tail (meaning Attorney General Robert Kennedy.) Whereas if you cut off the dog's head, (meaning President Kennedy) it would cease to cause trouble. Becker reported that Marcello "clearly stated that he was going to arrange to have President Kennedy killed in some way." Marcello told another informant that he would need to take out "insurance" for the assassination by "setting up some nut to take the fall for the job, just like they do in Sicily."