Wis. Stat. § 979.015

Upon the request of the coroner, medical examiner or district attorney, a court shall issue a subpoena requiring the production of documents necessary for the determination of a decedent’s cause of death. The documents may include the decedent’s patient health care records and treatment records, as defined in ss. 51.30 and 146.81 (4). The documents shall be returnable to the officer named in the subpoena.