1. A grand jury may hear and examine evidence concerning the alleged commission of any offense prosecutable in the courts of the county, and concerning any misconduct, nonfeasance or neglect in public office by a public servant, whether criminal or otherwise. 2. District attorneys are required or authorized to submit evidence to grand juries under the following circumstances: (a) A district attorney must submit to a grand jury evidence concerning a felony allegedly committed by a defendant who, on the basis of a felony complaint filed with a local criminal court of the county, has been held for the action of a grand jury of such county, except where indictment has been waived by the defendant pursuant to article one hundred ninety-five. (b) A district attorney must submit to a grand jury evidence concerning a misdemeanor allegedly committed by a defendant who has been charged therewith by a local criminal court accusatory instrument, in any case where a superior court of the county has, pursuant to subdivision one of section 170.25, ordered that such misdemeanor charge be prosecuted

y a local criminal court accusatory instrument, in any case where a superior court of the county has, pursuant to subdivision one of section 170.25, ordered that such misdemeanor charge be prosecuted by indictment in a superior court. (c) A district attorney may submit to a grand jury any available evidence concerning an offense prosecutable in the courts of the county, or concerning misconduct, nonfeasance or neglect in public office by a public servant, whether criminal or otherwise.