By Daily Mail Reporter and Associated Press PUBLISHED: 11:48 EST, 28 September 2012 | UPDATED: 17:01 EST, 28 September 2012 Authorities drilled through concrete and removed soil samples in a modest Detroit-area neighbourhood today in the latest effort to find the remains of Teamsters boss Jimmy Hoffa, who disappeared in 1975. There was no sign of human remains, but test results of the soil could be ready by Monday, Roseville Police Chief James Berlin said. 'We're not sure if anything is down there. That's what this is all about,' Berlin said. Scroll down for video Digging: A Roseville police officer stands by the door of a shed as a worker prepares to drill through a concrete floor to remove wet soil samples
@highlight
Teamsters boss last seen at suburban Detroit restaurant on July 30, 1975
@highlight
Man in Roseville, Michigan, claims he witnessed Hoffa's burial
@highlight
Cops say the homeowner, has lived at the home for a little more than a decade, and is being cooperative with their investigation
@highlight
FBI remains skeptical over the tip
@placeholder is one of several inner-ring communities that grew quickly as unionized auto factory workers left the city in search of nicer homes and bigger yards.