Police began drilling Friday outside a suburban Detroit home in the search for Jimmy Hoffa, the labor strongman whose disappearance is one of the most notorious and mysterious in U.S. history.

A tipster told police that a body was buried at the spot in Roseville, Michigan, about the time the Teamsters boss disappeared in 1975.

The tipster did not claim it was Hoffa's body, authorities said.

Police Chief James Berlin said Thursday that while the tipster's information seems credible, he's not convinced the body is Hoffa's because of the timeline. He spoke with the tipster August 22 and believes the person did see a burial.

The tipster did not come forward sooner out of fear, Berlin said.

Dan Moldea, author of "The Hoffa Wars," said the tipster, a former gambler, contacted him March 30. The tipster used to do business with a man who had ties to Anthony Giacalone, an organized crime figure who was supposed to meet Hoffa the day he disappeared, Moldea said.

"I am very skeptical," Moldea said of the planned dig. If Hoffa's burial had taken place at the spot, it would have been in full view of the neighborhood, the author argued.

And if Hoffa's body was disposed of, it would have been done in a way that no evidence would be left years later, he said.

It shouldn't take long to get a sample, which will be sent to Michigan State University for analysis, CNN affiliate WXYZ reported.

The reading will determine whether there are human remains at the site but will not identify them, Berlin said.

"It took us a while to get the proper equipment to do what we're going to do. If this is a person, they've been down there for 35 years. What's a few more days?" Berlin asked.

Results from the soil testing should be available next week, the chief said Wednesday.

"If they are positive, we will then start excavating," Berlin said.

The alleged burial site is under a concrete slab, and the residence is occupied by new homeowners, who've been "cooperative and excellent to police," Berlin said.

The FBI in Detroit had no comment on the planned search, and a statement from the International Brotherhood of Teamsters said the Hoffa family had nothing to say at this time.

"The Hoffa family does not respond every time a tip is received by authorities. The FBI keeps the family informed, and they will have no comment until there is a reason to comment," the statement said.

Hoffa remains among America's most famous, and in many ways infamous, missing people. His presumed death has vexed investigators for four decades.

One of the most powerful union leaders at a time that unions wielded a great deal of sway over elections -- and were notoriously tied to organized crime -- Hoffa was forced out of the organized labor movement when he was sent to prison in 1967.

He served time for jury tampering and fraud at a federal penitentiary in Lewisburg, Pennsylvania, until being pardoned by President Richard Nixon on December 23, 1971 -- on the condition that he not try to get back into the union movement before 1980.

Two weeks before Hoffa's disappearance in 1975, federal investigators discovered that hundreds of millions of dollars had been stolen from the Teamsters' largest pension fund, Time magazine points out in its list of the top 10 most famous disappearances.