California Code, Penal Code - PEN § 939.91

(a) A grand jury which investigates a charge against a person, and as a result thereof cannot find an indictment against such person, shall, at the request of such person and upon the approval of the court which impaneled the grand jury, report or declare that a charge against such person was investigated and that the grand jury could not as a result of the evidence presented find an indictment. The report or declaration shall be issued upon completion of the investigation of the suspected criminal conduct, or series of related suspected criminal conduct, and in no event beyond the end of the grand jury's term.

(b) A grand jury shall, at the request of the person called and upon the approval of the court which impaneled the grand jury, report or declare that any person called before the grand jury for a purpose, other than to investigate a charge against such person, was called only as a witness to an investigation which did not involve a charge against such person. The report or declaration shall be issued upon completion of the investigation of the suspected criminal conduct, or series of related suspected criminal conduct, and in no event beyond the end of the grand jury's term.