An information may be filed by the attorney for the Commonwealth based upon a complaint in writing verified by the oath of a competent witness; but no person shall be put upon trial for any felony, unless an indictment or presentment shall have first been found or made by a grand jury in a court of competent jurisdiction or unless such person, by writing signed by such person before the court having jurisdiction to try such felony or before the judge of such court shall have waived such indictment or presentment, in which event he may be tried on a warrant or information. If the accused be in custody, or has been recognized or summoned to answer such information, presentment or indictment, no other process shall be necessary; but the court may, in its discretion, issue process to compel the appearance of the accused.