Agents and New York City police officers spent nearly a week tearing up the SoHo-district building's basement but uncovered no remains or personal effects of the 6-year-old boy, who vanished while walking to his school bus stop.
Etan was one of the first missing children in the United States to have his photo printed on milk cartons.
Law enforcement sources told the New York Post that strands of hair recovered at the scene did not appear to match the missing boy's hair.
The lack of new evidence prompted an attorney representing a one-time prime suspect in the case, 75-year-old Othniel Miller, to again deny any role in the disappearance and say his client's reputation was being sullied by the renewed media focus.
Celebrity Families of 2014 [PHOTOS]