MILFORD TOWNSHIP, Mich. (AP) – After tearing apart a barn, FBI agents began digging up the ground where it stood Thursday, taking photos and video and sifting through dirt by hand as they searched for Jimmy Hoffa’s remains at a suburban Detroit farm.

After a backhoe dug a hole at the site, FBI agents and crime-scene investigators jumped in to take pictures and comb through the soil. At one point, two dogs were sent into the hole. But after seven hours of digging, FBI spokeswoman Dawn Clenney said nothing significant was found.

“Much ado about nothing,” Clenney said. She said the search was expected to continue through the Memorial Day holiday weekend.

The 100-by-30-foot barn was torn down Wednesday as the FBI scoured Hidden Dreams Farm, which once was owned by a Hoffa associate and is located not far from where the former Teamsters chief vanished in 1975. Before the dig began Thursday, authorities removed a layer of concrete and asphalt that had been the floor of three rooms inside the building.

The search of the Milford Township farm, 30 miles northwest of Detroit, began May 17. Officials have said the search would last a couple of weeks and involve cadaver dogs, demolition experts, archaeologists and anthropologists.

Bill Koresky, whose company was hired by the FBI to knock down the barn and dig beneath it, said the digging was stopped when a university professor who is leading the work noticed a change in the color of the dirt and a piece of what looked like rotted wood.

“You’ll see the color will be different, I don’t care if it’s 70 or 80 years” since the land was disturbed, said Koresky, the co-owner of Able Demolition of Sterling Heights who ran one of the excavation machines at the site on Wednesday and Thursday.

Cadaver dogs were sent into the hole but turned up nothing significant, Clenney said.

Koresky said that before stopping for the day, crews had dug a 50- by 40-foot hole that was 3 1/2- to 4-feet deep. A trained eye, he said, can tell whether the dirt has been disturbed by digging to that depth.

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

No trace of Hoffa has ever been found, and no one has ever been charged in his disappearance.

A government investigator said last week that Donovan Wells, who lived on the land at the time, gave the FBI the tip that sparked the intense effort to solve the legendary mystery. The investigator is familiar with the current dig and spoke on condition of anonymity because some of his information came from records that have been ordered sealed by a federal judge.

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 fish in a Florida swamp; that he was obliterated in a mob-owned fat-rendering plant that has since burned down.