Hoffa was president of the Teamsters union until 1971. Zerilli has been promoting a book, "Hoffa Found." A website says the book will reveal details about Hoffa's death.

Son Jim Hoffa, the Teamsters' president, recently told The News that Zerilli's tip may have some legitimacy because Zerilli was a top figure in the Detroit mob.

"When he says something, you have a tendency to believe it," Hoffa said. "This isn't just some guy that wants to sell a book."

He noted that repeated searches have given the family false hope.

"It's very hard on the family to go through this again and again and again," he said. "It's very hard because people make jokes on television."