Pennsylvania Statutes Title 42 Pa.C.S.A. Judiciary and Judicial Procedure § 5904. Subpoena of witnesses

(a) Method of service.--In addition to any other method of service provided by law, a subpoena may be served upon a witness in a criminal proceeding by registered or certified mail, return receipt requested, or by first class mail.

(b) Proof of service.--A completed return receipt shall be prima facie evidence of service of the subpoena.

(c) Duration.--A subpoena shall remain in force until the termination of the criminal proceeding.

(d) Bench warrants.--Upon proof of service of a subpoena, the court may issue a bench warrant for any witness who fails to appear in response to a subpoena. However, such warrant cannot be issued if service has been by first class mail.