Within 5 days after the answer to the charge has been or should have been filed, the panel may refer the matter, accompanied by a general or particularized request, to the National Center for Dispute Settlement of the American Arbitration Association (hereinafter referred to as the Center) to make an investigation and to determine whether the charging party has established a prima facie case.

For the purposes of this part, a prima facie case means a case where allegations of an unfair labor practice that have been presented give reasonable cause to believe that such practice may have occurred, but where evidentiary proceedings are necessary for determination of whether the allegations are substantiated.

The Center may use its own personnel or may hire individuals on a contract basis to conduct such investigations. The panel may consolidate or sever proceedings conducted pursuant to this part.

Any party may request the Center or other appointing authority to withdraw appointment of the investigator within 3 days after designation on the basis of previously demonstrated personal bias, conflict of interest, or prejudice. Such a request shall set forth in detail the matter alleged to constitute grounds for disqualification. Denial of a request by the Center or other appointing authority shall be substantiated in writing and transmitted to the requesting party, and shall be submitted to the panel together with the complete report of the investigator required in § 269b.240(b).