Wis. Stat. § 968.44

The presiding juror of every grand jury and the district attorney or other prosecuting officer who is before the grand jury may administer all oaths and affirmations in the COMMENCEMENT OF CRIMINAL PROCEEDINGS 968.5327 manner prescribed by law to witnesses who appear before the jury for the purpose of testifying in any matter of which the witnesses have cognizance. At the request of the court, the presiding juror shall return to the court a list, under his or her hand, of all witnesses who are sworn before the grand jury. That list shall be filed by the clerk of circuit court.