California Code, Penal Code - PEN § 919

(a) The grand jury may inquire into the case of every person imprisoned in the jail of the county on a criminal charge and not indicted.

(b) The grand jury shall inquire into the condition and management of the public prisons within the county.

(c) The grand jury shall inquire into the willful or corrupt misconduct in office of public officers of every description within the county.Except as provided in Section 918, this subdivision does not apply to misconduct that involves a shooting or use of excessive force by a peace officer described in Section 830.1, subdivision (a) of Section 830.2, or Section 830.39, that led to the death of a person being detained or arrested by the peace officer pursuant to Section 836.