16 Pa. Stat. § 1409
If any district attorney shall neglect or refuse to prosecute in due form of law any criminal charge regularly returned to the district attorney or to the court , or if at any stage of the proceedings the district attorney and the private counsel employed by the prosecutor shall differ as to the manner of conducting the trial, the prosecutor may present a petition to the court , setting forth the character of the complaint, and verify the same by affidavit. If the court shall be of the opinion that it is a proper case for a criminal proceeding or prosecution, it may direct any private counsel employed by such prosecutor to conduct the entire proceeding, and where an indictment is necessary, to verify the same by the private counsel's own signature, as fully as the same could be done by the district attorney.
16 P.S. § 1409