FBI agents on Thursday began digging through the dirt at the site where a barn once stood as they continued the search for the remains of Jimmy Hoffa at a suburban Detroit farm, and at one point brought in dogs to search in the hole.

The searchers used a backhoe to peel away the earth at the spot where they had removed a layer of concrete and asphalt that had been the barn's floor.

By early afternoon, the digging stopped and FBI agents and crime scene investigators jumped in the hole to take photos and video and sift through the dirt by hand. At one point, two dogs were sent into the hole as FBI agents huddled nearby.

The 100-by-30-foot barn was torn down Wednesday, its pieces trucked off to a landfill as the FBI continued its efforts to solve the 30-year-old mystery of Hoffa's disappearance. All that was left was the barn's 200-square-foot, 4-inch-thick floor, which was removed by a 75,000-pound excavation machine Thursday morning.

"Today is gonna mean something," said Bill Koresky, an employee of Able Demolition of Sterling Heights, who operated the excavation machine.

It took about three hours for Koresky's machine to gobble up the barn Wednesday in the most dramatic moment since dozens of FBI agents descended on the Hidden Dreams Farm, 30 miles northwest of Detroit.

The machine slammed its jaws into the structure, startling two horses who ran to the edge of their pasture. It then gnawed at the barn's siding, taking huge bites and tossing debris into a pile.

The machine then loaded the debris into a pair of semi-trucks, which transported it to a landfill.

FBI agents pulled wood from the rubble and inspected it, while others took video and still photographs of the demolition. Dawn Clenney, a spokeswoman for the FBI in Detroit, said afterward that the demolition was part of the broader search effort.

"We would like to dig underneath that area," she said. "That's a site that we are interested in."

Donald Shouse of nearby Highland Township, who has done business on the horse farm for three decades, said the structure was built sometime in the 1970s and was the oldest barn on the site.

Most of its floor was dirt, but it had about 200 square feet of concrete above which were three rooms. The horse stalls inside the barn had dirt floors, Shouse said.

While it was expected to cost $6,000 to remove the barn, the FBI has said it does not have an estimate on the total cost of the search, which began May 17 at the Hidden Dreams Farm in Milford Township. Officials have said the search would last a couple of weeks and involve cadaver dogs, demolition experts, archaeologists and anthropologists.

Clenney said Wednesday night that nothing significant has been found so far.

The farm once was owned by a Hoffa associate and is located not far from where the former Teamsters chief vanished in 1975. No trace of the former Teamsters leader has ever been found, and no one has ever been charged in the case.

A government investigator said last week that Donovan Wells, who lived on the land at the time, was the one who gave the FBI the tip that has sparked the intense effort to solve a legendary mystery.

Wells' lawyer, Joseph J. Fabrizio, said that his client told the FBI in 1976 that he saw suspicious activity on the farm around the time of Hoffa's disappearance.

The investigator said that Wells wasn't that forthcoming 30 years ago and that he recently passed a polygraph exam. The investigator is familiar with the current dig and spoke on condition of anonymity because some of his information comes from records that have been ordered sealed by a federal judge.

Another former lawyer for Wells, James Elsman, said Wells said he actually saw a grave being dug with a backhoe. He claims that based on what Wells told him in 1976, he could pinpoint the location.

Hoffa last was seen on a night he was scheduled to have dinner at a restaurant about 20 miles from the farm. He was supposed to meet with a New Jersey Teamsters boss and a Detroit Mafia captain, both now dead.

Over the years, Hoffa's disappearance spawned endless theories — that he was entombed in concrete at Giants Stadium in the New Jersey Meadowlands; that he was ground up and thrown to the fishes in a Florida swamp; that he was obliterated in a mob-owned fat-rendering plant that has since burned down.