Charles "Chuckie" O'Brien, a longtime associate of Teamsters boss Jimmy Hoffa who became a leading suspect in Hoffa's disappearance, has died. O'Brien's stepson, Harvard Law School professor Jack Goldsmith, said in a blog post that O'Brien died Thursday in Boca Raton, Florida, from what appeared to be a heart attack. He was 86. O'Brien was a constant companion to Hoffa in the decades when the labor leader developed the Teamsters into one of the largest and most powerful unions in the nation. After Hoffa's still-unsolved disappearance in 1975, O'Brien became a leading suspect. O'Brien was portrayed by actor Jesse Plemons in the 2019 Martin Scorsese film "The Irishman."