A few days ago I finished reading "I Heard You Paint Houses" which is a nonfiction book written by former homicide prosecutor, investigator, and defense attorney Charles Brandt that chronicles the life of Frank Sheeran, an alleged mafia hitman who confesses the crimes he committed working for the Bufalino crime family, including killing Jimmy Hoffa.
The book was made into a movie "The Irishman" directed by Martin Scorsese and you can watch it via Netflix. Great movie, but you should also definitely read the book.
I'm fairly certain that what is written in the book is what happened to Jimmy Hoffa 46 years ago.
The FBI seems to think a lot of what has been written in this is also quite plausible.
Check it out, or at least watch the movie.