This isn't really news, but
"I Heard You Paint Houses" (written by Charles Brandt, but essentially the memoirs of Sheeran) is probably as close as we're going to get to knowing what happened considering who's still left alive that might have been involved.
In case you don't want to read the book (which I highly recommend, jam packed with Teamster history) History Detectives did a special recently centered around the book:
http://www.pbs.org/opb/historydetectives/investigation/who-killed-jimmy-hoffa/