I believe Goldsmith. His "In Hoffa's Shadow" isn't a comprehensive bio of Hoffa, but it has plenty enough good info to keep any reader informed. I don't think he even mentioned Sheerann in that book.

If I remember correctly, in the first edition of "I Hear You Paint Houses," Brandt said Sheeran told him he was in the house where Hoffa was killed, but didn''t pull thr trigger. Nor did Sheeran identify the actual killer, now thought to be Anthony "Tony Pal" Palozzolo.