Joe Valachi (1903-1971)

Joseph Valachi, sometimes called “Joe Cargo”, has the ill reputation of being the first member of the mafia to reveal the existence of the organization during his testimony before the U.S. Congress’ McClellan Commission on Organized Crime. His testimony will notably reveal to the public the monicker “Cosa Nostra”. His motives for giving up this information remain obscure. Some say he had psychological problems (many members of his family had mental health issues, and two relatives committed suicide), while others believe he was trying to get a reduced sentence for a murder he committed in 1962. His employer, Vito Genovese, put a 100 000$ contract on his life for breaking the Omertà. He will be jailed in a heroin trafficking affair and will die in jail of a heart attack in 1971.

Source:
http://en.wikipedia.org/wiki/Joseph_Valachi