FBI agents dug up a Detroit lumberyard for a second day today, but were mum on speculation that the excavation was a renewed search for the body of Jimmy Hoffa.
At the scene on Tuesday, FBI spokeswoman Sandra Berchtold said the operation is continuing and it will continue throughout the day.
"Until we're complete, we'll be here," she said.
Berchtold said only that the digging is part of a joint FBI and Detroit Police investigation. She would not comment on speculation that the FBI is looking for Hoffa nor would she elaborate on exactly what the agents were looking for.
"We are executing a federal search warrant and the affidavit is sealed," she said.
A spokesman for the Detroit police said he did not know what the FBI is searching for because the department is only involved in "peripheral" way.
Hoffa, the long-time president of the powerful International Brotherhood of Teamsters union, was last seen in 1975 outside a suburban Detroit restaurant called "The Red Fox." Though the FBI won't discuss the investigation, there are a couple of reasons why speculation abounds that officials are looking for Hoffa's body.
ABC station WXYZ reported Monday that the investigators at the site could be seen carrying binders that said "Big Dig 2." In May 2006, a search for Hoffa at a farm in Milford, Mich., was known as the "Big Dig."
At the conclusion of the investigation in 2006, the FBI said it would continue to investigate Hoffa's disappearance. Assistant special agent of the FBI Judith Chilen said at the time, "There are still prosecutable defendants, and they know who they are."
The current search began Monday when the officials used a large excavator to clear brush, tires and to dig holes at the site. Search dogs could also be seen at the scene assisting the investigators.
Officials have erected a fence with a tarp at the site, which has largely blocked a view of the work. FBI agents remained at the scene Monday night after investigators wrapped up the first day of the search for security reasons, Berchtold said.
Other Hoffa excavations have included a backyard pool north of Detroit in 2003 and they searched a Detroit home in 2004.
Hoffa's disappearance has fascinated the public for many years. Authorities and historians alike have theories about what happened to the labor boss.
Among the most popular ideas is that Hoffa was buried at Giants Stadium in the New Jersey Meadowlands or diced up at a mob-owned fat-rendering plant.
A Detroit police officer who researched the mystery of Hoffa's disappearance for three years has written a book detailing his findings. Jeff Hansen, author of the book "Digging for the Truth: The Final Resting Place of Jimmy Hoffa," says Hoffa's remains are inside a mausoleum at Detroit cemetery. Hoffa was cremated after he was shot inside his Detroit home, Hansen explains in the book.
The Detroit Free Press reports that several people directly or indirectly involved in the investigation cast doubt on Hansen's claims. One of the original agents on the Hoffa case said the theory in Hansen's book doesn't square with the interviews the FBI conducted.