What is the legal test for an allegation of criminal activity before a grand jury?

In the prosecution of a felony, the People may proceed either by indictment or information. ( Cal. Const., art. I, 14 ; 682, 737.) "An indictment is an accusation in writing, presented by the grand jury to a competent court, charging a person with a public offense." ( 889.) "Thus, under the statutory scheme, it is the grand jury's function to determine whether probable cause exists to accuse a defendant of a particular crime." ( Cummiskey v. Superior Court (1992) 3 Cal.4th 1018, 1026, 13 Cal.Rptr.2d 551, 839 P.2d 1059.)