16 Pa. Stat. § 4406
If the district attorney is charged, according to law, with any crime or misdemeanor before or bound over or committed by any court to answer for wilful and gross negligence in the execution of the duties of his office, it shall be the duty of the court to appoint some competent attorney thereof to prepare an indictment against such district attorney and to prosecute the same on behalf of the Commonwealth until final judgment. Such attorney shall be paid by the county for his services a reasonable compensation to be fixed by the court. If such district attorney shall be convicted of any crime for which he may be sentenced to imprisonment by separate or solitary confinement at labor, his office shall be declared vacant by the court.
16 P.S. § 4406