Question: The Valachi hearings, also known as the McClellan hearings, investigated organized crime activities across America, the hearings were named after which American gangster, notable as the first member of the Italian-American Mafia to publicly acknowledge its existence,was a major government witness against the American Mafia?
Sentence (from "Valachi hearings"): 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.
Relevant evidence: No