(CNN) -- He's still missing.
The seemingly never-ending search for the remains of missing Teamster boss Jimmy Hoffa hit another dead end Tuesday when soil results taken from the grounds of a home in Michigan showed no evidence that human remains were buried on the property.
Two soil samples were taken from a home in the suburban Detroit community of Roseville last week after a tipster claimed he saw a body buried in the yard a day after Hoffa disappeared in 1975.
The samples were taken from beneath a storage shed and sent to a lab at Michigan State University for tests to determine the presence of human remains.
"The samples submitted for examination showed no signs of human decomposition," a statement from Roseville Police Chief James Berlin said Tuesday.
It is the latest act in the on-again, off-again search for Hoffa, whose disappearance 35 years ago captured the public imagination.
Hoffa, then 62, was last seen on July 30, 1975, outside the Detroit-area Machus Red Fox restaurant. He was there ostensibly 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.
The tipster, a former gambler, once did business with a man tied to Giacalone, said Dan Moldea, author of "The Hoffa Wars." Moldea said he first spoke to the tipster in March and then sent him to police.
Vanished Hoffa still fascinates after almost 40 years
Berlin said the "timeline doesn't really add up" because the tipster said he went to the house to repay a bookie -- who didn't live at that address until years after Hoffa disappeared.
Still, the man said he thought he saw what could have been a body taken into the shed.
Moldea said it seemed 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 said.
"This is kind of like an open wound that won't go away," Berlin said Monday. "Every couple of years this happens, and all you guys come out here and we have to relive it."
Hoffa was one of the most powerful union leaders at a time when unions wielded enormous political sway. He was forced out of the organized labor movement when he went to federal prison in 1967 for jury tampering and fraud.
President Richard Nixon pardoned him in 1971 on condition he not attempt to get back into the union movement before 1980.
Hoffa believed Giacalone had set up the meeting to help settle a feud between Hoffa and Provenzano, but Hoffa was the only one who showed up for the meeting, according to the FBI. Giacalone and Provenzano later told the FBI that no meeting had been scheduled.
The FBI said at the time that the disappearance could have been linked to Hoffa's efforts to regain power in the Teamsters and the mob's influence over the union's pension funds.
Police and the FBI have searched for Hoffa intermittently.
In September 2001, the FBI found DNA that linked Hoffa to a car that agents suspected was used in his disappearance.
In 2004, authorities removed floorboards from a Detroit home to look for traces of blood, as former Teamsters official Frank Sheeran claimed in a biography that he had shot Hoffa. Sheeran died in 2003.
Two years later, the FBI razed a horse barn in Michigan following what it called "a fairly credible lead."
Urban lore long suggested that Hoffa was buried around the end zone at the former Giants Stadium in New Jersey.
CNN's Chuck Johnston and Stephanie Gallman contributed to this report.