The Valachi hearings, also known as the McClellan hearings, investigated organized crime activities across America and investigated leading mafia figures of the era such as Sam Giancana of Chicago. The hearings were initiated by Arkansas Senator John L. McClellan in 1963. The hearings were named after the major government witness against the American Mafia, Joseph Valachi.
In October 1963, Valachi testified before Senator John L. McClellan's congressional committee on organized crime, the Permanent Subcommittee on Investigations of the U.S. Senate Committee on Government Operations. He gave the American public a firsthand account of Mafia activities in the United States. According to a Justice Department official Valachi "showed us the face of the enemy."
Valachi, a low-ranking member of the New York-based Genovese crime family, was the first ever government witness coming from the American Mafia itself. Before Valachi, federal authorities had no concrete evidence that the American Mafia even existed. His disclosures never led directly to the prosecution of many Mafia leaders, but he was able to provide many details of its history, operations and rituals, aiding in the solution of several uncleared murders, as well as naming many members and the major crime families.
Valachi testified in vivid and minute detail on his day-to-day life in organized crime in a first-time-ever public account of life as a soldier of La Cosa Nostra, including its rites of initiation. These televised hearings brought home to average Americans the savage violence and intimidation routinely used by the Mafia to further and protect its criminal enterprises.