Working from a tip given by an aging mobster, the FBI began digging in a overgrown field in Detroit in search for the missing body of former Teamster boss, Jimmy Hoffa. Hoffa's remains have been missing for nearly four decades.

Tony Zerilli, the alleged mobster and son of Joseph Zerilli, is apparently a "highly credible" source. Zerilli claims that Hoffa was struck with a shovel to knock him out, and then buried alive under a concrete slab. The FBI reports that they looked into Zerilli's claims for months before beginning the excavation of the field. Zerilli discredited previous connections between New Jersey crime boss Tony Provenzano, and said it was Detroit mobsters who wanted Hoffa killed. In a manuscript for sale at HoffaFound.com, he wrote:

"There was an old house with an old barn on the property. As soon as they pulled near the barn, Hoffa was dragged out of the car, and bound and gagged. A shallow hole was already dug in the barn floor. He put up a fight, but he was easily overpowered. …(One of the men) picked up a shovel and cracked Hoffa over the head with it. …They threw him into the hole, and buried him alive. He wasn’t shot, he wasn’t stabbed, nothing like that. A cement slab of some sort was placed on top of the dirt to make certain he was not going to be discovered. And that was it. End of story.”

Hoffa was last seen in July 1975, outside a Detroit restaurant. He was 62. Zerilli, who denies any participation in Hoffa's disappearance, was in jail at the time that Hoffa went missing.

Hoffa's missing remains have been a longtime obsession and mystery, since his disappearance 38 years ago. Tips crop up with some frequency. Last October, someone suggested Hoffa might be buried in a yard in a Detroit suburban community, but soil samples showed up negative. In 2010, there was some to-do after authorities stated they would not search for Hoffa before the Giants stadium was demolished. In 2004, a Detroit home was torn up as authorities searched under the floorboards looking for blood after Teamster Frank Sheeran claimed he shot Hoffa, before Sheeran died in 2003. Nothing was discovered.

Digging will begin again at 8 a.m this morning.

UPDATE 12:17 p.m. June 18: Investigators have unearthed two concrete slabs, but no body as of yet.

[CNN | Detroit Free Press, image via AP]