Oakland Township, Michigan (CNN) -- The FBI on Tuesday spent a second day digging in a Detroit-area field in the latest search for the remains of former Teamsters boss Jimmy Hoffa -- an effort spurred by information from an aging reputed mobster. Agents began digging Monday in waist-high grass in Oakland Township north of Detroit, a location determined in part from information provided by alleged mobster Tony Zerilli. Media and curious onlookers gathered some distance from the private property. The search was stopped for the night as evening approached but will resume Wednesday at 8 a.m. Nothing yet has been found, two law enforcement sources familiar with the investigation said Tuesday afternoon. Oakland Sheriff Mike Bouchard said investigators are using probes to determine what the ground makeup is, but have not found samples that would require lab analysis.
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NEW: Alleged mobster who tipped off police says he hopes his "good friend" is exhumed
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Search has ended for the night, will resume Wednesday morning
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Concrete slabs are removed during the dig, a source says
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Hoffa, then 62, was last seen on July 30, 1975, outside a Detroit-area restaurant
The FBI spent months looking into @placeholder's claims before seeking court authorization to excavate the field and look for evidence of a shallow grave, according to a law enforcement source.
@placeholder was freed in 2008 after his last prison sentence.