5. Sam Giancana
Sam Giancana was a Sicilian American mob boss of the Chicago Outfit. Giancana was assassinated in 1975 – before any serious charges could be pinned on him. Giancana’s killer is thought to have been either long-term confidante, Butch Blasi, or Anthony ‘Ant’ Spilotro, and possibly ordered by Anthony Accardo – another entrant on this dishonourable list. Giancana was killed at his home on the eve of federal agents taking him to Washington to testify – this guy knew too much and had to be taken out.
There are many people who believe he had turned informant and was in fact working with the CIA on a plot to assassinate Fidel Castro. In full disclosure, Giancana is included here even though served just one year for refusing to testify before a grand jury investigation – a lucky escape in the light of this guy’s true crimes.