A grand jury is a body of the required number of persons returned from the citizens of the county before a court of competent jurisdiction, and sworn to inquire of public offenses committed or triable within the county.

Each grand jury or, if more than one has been duly impaneled pursuant to Sections 904.4 to 904.8, inclusive, one grand jury in each county, shall be charged and sworn to investigate or inquire into county matters of civil concern, such as the needs of county officers, including the abolition or creation of offices for, the purchase, lease, or sale of equipment for, or changes in the method or system of, performing the duties of the agencies subject to investigation pursuant to Section 914.1.