A cadaver dog, working with FBI investigators in an abandoned field about a half hour's drive away from where Hoffa was last seen on July 30, 1975, "reacted to some scents" at the dig site Tuesday afternoon. Investigators said they were not sure what -- if anything -- the dog was reacting to.
Some bones had been found in the field, a former farm, but none were human bones, said Oakland County Sheriff Mike Bouchard.
Earlier in the day, searchers turned up a "suspicious" slab at the dig site, but it is too soon to know if the cement is just the old foundation of a barn -- or Hoffa's concrete coffin.
The FBI were pointed to the field in Oakland Township by an ex-mobster Tony Zerilli, who was in prison at the time of Hoffa's disappearance but said he was told of Hoffa's fate after his release.
Zerilli said Hoffa, who was last seen at a restaurant in Bloomfield Township, was abducted, hit on the head with a shovel, buried in a shallow grave and covered in concrete on a property once owned by mob boss Jack Tocco.