Mass. Gen. Laws ch. 276, § 22: Warrants, procedure for issuance

Section 22. Upon complaint made to any justice that a crime has been committed, he shall examine on oath the complainant and any witnesses produced by him, reduce the complaint to writing, and cause it to be subscribed by the complainant, and, if it appears that a crime has been committed, shall issue a summons or warrant in compliance with the provisions of the Massachusetts Rules of Criminal Procedure.