29 C.F.R. § 23.430
The Administrator may investigate possible violations of the Executive Order or this part either as the result of a complaint or at any time on his or her own initiative. As part of the investigation, the Administrator may conduct interviews with the relevant contractor, as well as the contractor's workers at the worksite during normal work hours; inspect the relevant contractor's records (including contract documents and payrolls, if applicable); make copies and transcriptions of such records; and require the production of any documentary or other evidence the Administrator deems necessary to determine whether a violation, including conduct warranting imposition of debarment, has occurred. Federal agencies and contractors shall cooperate with any authorized representative of the Department of Labor in the inspection of records, in interviews with workers, and in all aspects of investigations.
29 C.F.R. §23.430