Jimmy Hoffa Agreement. He played a major role in the growth and development of the union, which eventually became the largest (by membership) in the United States with over 2.3 million members at its peak, during his terms as its leader. Hoffa became involved with organized crime from the early years of his Teamsters work, and this connection continued until his disappearance in 1975. He was convicted of jury tampering, attempted bribery and fraud in 1964, in two separate trials. He was imprisoned in 1967 and sentenced to 13 years. In mid-1971, he resigned as president of the union as part of
Jimmy Hoffa caused by the 1975 disappearance of her husband, because her health had declined steadily since then. She is entombed in Michigan. In 1989, Kenneth Walton, the head of the FBI's Detroit office, told "The Detroit News" that he knew what happened to Hoffa. "I'm comfortable I know who did it, but it's never going to be prosecuted because ... we would have to divulge informants, confidential sources." In 2001, the FBI matched DNA from Hoffa's hair—taken from a brush—with a strand of hair found in a 1975 Mercury Marquis Brougham driven by longtime friend Charles "Chuckie" O'Brien on July 30,