MILFORD TOWNSHIP, Mich. – In one of the most intensive searches for Jimmy Hoffa in decades, the FBI summoned archaeologists and anthropologists and brought in heavy equipment to scour a horse farm yesterday for the body of the former Teamsters boss who vanished in 1975.

The agent in charge of the Detroit FBI field office, Daniel Roberts, would not disclose what led agents to the farm, but said: “This is probably a fairly credible lead. You can gather that from the number of people out here.”

No trace of Hoffa has ever been found, and no one has ever been charged in the case. But investigators have long suspected that he was killed by the mob to keep him from reclaiming the Teamsters presidency after he got out of prison for corruption.

The farm, just outside Detroit, used to be owned by a Teamsters official. And mob figures used to meet at a barn there before Hoffa’s disappearance, authorities said.

Investigators began scouring the area Wednesday, and the search continued yesterday and included the use of heavy construction equipment. Mr. Roberts said it would probably involve the removal of a barn.

Authorities also led cadaver dogs across the property, and the FBI called in anthropologists and archaeologists from Michigan State University.

Mr. Roberts said he expects the search to go on for at least a couple of weeks.

Hoffa was last 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; 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.

In 2003, authorities searched beneath a backyard pool a few hours north of Detroit but turned up nothing. The following year, they pulled up the floorboards on a suburban Detroit home and found bloodstains, but the blood was not Hoffa’s.

A law enforcement official in Washington said the latest search was based on information developed several years ago and verified more recently.

Among other things, there was a high level of suspicious activity on the farm the day Hoffa vanished, the official said, speaking on condition of anonymity. A backhoe appeared that day near the barn organized crime members had used for meetings, and that location was never used again, the official said.

At the time of Hoffa’s disappearance, the property was owned by a longtime Teamsters official, Rolland McMaster. It is now under different ownership and is called Hidden Dreams Farm.

McMaster’s lawyer, Mayer Morganroth, said he doubted the FBI would find anything. “That farm was looked at with a fine-toothed comb in the ’70s, when Hoffa was missing,” Mr. Morganroth said. “There’s nothing there.”

McMaster was convicted in 1963 of accepting payoffs from a trucking company and, according to a 1976 Detroit Free Press account, served five months in prison.

Reporters were not allowed onto the property, which is surrounded by a white wooden fence just off a dirt road. Images from news helicopters showed about a dozen people, some with shovels, standing by an area of newly turned dirt about 10 feet by 15 feet.