La. Code Crim. Proc. art. 415.1
Upon the request of the district attorney, the court shall order one or more additional grand juries to be impaneled. Such additional grand juries shall be selected in the same manner and have the same qualifications, duties, powers, and responsibilities, and be subject to the same provisions of law which presently govern grand juries, except as to duration and the duty to inspect facilities as provided by R.S. 15:121. However, no grand jury may concurrently conduct an inquiry into any offense or matter or receive evidence of any offense or matter which is under investigation by another grand jury impaneled in the same parish. These additional grand juries shall be impaneled and presided over by the judge who impaneled the existing regular grand jury or a judge appointed by him to act in his absence.
La. Cr.P. § 415.1