The two soil samples extracted from a home in the suburban Detroit community of Roseville last week were taken to Michigan State University after a tipster claimed he saw a body buried on the property a day after Hoffa disappeared in 1975.
The samples were taken from beneath a storage shed for testing despite the fact that a search last week failed to turn up any "discernible remains," such as bones, body parts or other evidence, Roseville Police Chief James Berlin said.
The search of the Detroit home is the latest in a string of efforts to find the body of Hoffa, who was 62 when he was last seen on July 30, 1975, outside the Detroit-area Machus Red Fox restaurant.
Multiple reports indicate that he was set to meet with reputed Detroit Mafia street enforcer Anthony Giacalone and Genovese crime family figure Anthony Provenzano, who was also a chief of a Teamsters local in New Jersey. Giacalone died in 1982; Provenzano died in 1988 in prison.
Authorities in Detroit are acting on a tip received by a man who told Dan Moldea, author of "The Hoffa Wars," that he once did business with a man tied to Giacalone. Moldea told CNN that he first spoke to the tipster in March and then sent him to police.
Despite the story and tips he has given investigators, Moldea said it seems unlikely that anyone would have been buried at the site, in full view of the neighborhood. And if a body had been buried there, little would remain, he told CNN.
As previously reported, the lab tests being conducted on the soil samples will be able to determine if human remains were buried at the site but will not identify them, Berlin said.
Berlin added that if human remains are discovered, investigators would have to return for a more complete excavation.
Even so, Berlin doubts any possible human remains discovered at the house would be those of Hoffa.
"It would be great if it was, because I would like to bring closure to his family and the tens of thousands of Teamsters that idolize this man and just the southeast of Michigan," said Berlin, of the Roseville Police Department.
"This is kind of like an open wound that won't go away. Every couple of years this happens, and all you guys come out here, and we have to relive it."