The FBI is surveying a former New Jersey landfill — once condemned as an environmental disaster site — as part of the agency's long-running investigation into the disappearance of Jimmy Hoffa, the infamous Teamster labor union leader who mysteriously vanished in 1975.

Federal agents visited the site on Oct. 25 and 26 to conduct a "site survey," according to The New York Times. The survey follows the deathbed confession of a former landfill worker who claimed that "unidentified people" charged him and his father with burying Hoffa's body in a steel barrel roughly 15 feet (4.5 meters) below the dump in 1975.

The worker, Frank Cappola, was only 15 years old at the time, when he worked alongside his father at the PJP Landfill in Jersey City — today, just a small plot of dirt about the size of a Little League baseball diamond, the Times reported.

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In a sworn statement given before his death in 2020, Cappola recalled the day in 1975 when "a black limousine drove into our lot in the mud," and several strangers emerged to give his father and another site worker a set of instructions that Cappola wouldn't fully understand for decades to come. On his deathbed in 2008, Cappola's father told his son exactly what the men had discussed: that they would deliver Hoffa's dead body to the landfill, where the workers would cram it into a steel drum and bury it deep underground.

According to Cappola, his father used an excavator to dig a large hole just outside the boundaries of the landfill. Hoffa's body was delivered, then stuffed headfirst into a 55-gallon (208 liters) drum. Cappola's father first buried the barrel with Hoffa in it, then added 15 to 30 chemical drums on top of it, capped with some chunks of dirt and brick, Cappola said.

Though FBI agents visited the site with a search warrant later in 1975 — following a lead that Hoffa may have been buried in a New Jersey landfill — they didn't know where to dig, and they found nothing, the Times reported.

By 1983, the dump had become hazardous, with underground chemical fires burning day and night, and it was declared a Superfund site (that is, a polluted site requiring long-term action to clear hazardous contamination). "Thousands of barrels were dug up and carted away, and the landfill was capped," journalist Michael Wilson reported in the Times coverage. "In recent years, it was converted into the Skyway Park, a vibrant green belt along the Hackensack River."

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Through all of this, the alleged barrel containing Hoffa's remains was never found. The FBI investigators are currently analyzing their latest survey data to decide whether to excavate the site, said Special Agent Mara R. Schneider, a spokesperson for the FBI.

Hoffa's disappearance has captivated America for 45 years, most recently becoming the subject of the 2019 Martin Scorsese film "The Irishman." Hoffa had known ties to the New Jersey Mafia, and he was scheduled to have a meeting with local mob boss Anthony Provenzano (also known as "Tony Pro") on the day of his disappearance in July 1975, according to the Times.

Originally published on Live Science.