Wis. Stat. § 157.05: Autopsy.

Consent for a licensed physician to conduct an autopsy on the body of a deceased person shall be deemed sufficient when given by whichever one of the following assumes custody of the body for purposes of burial: Father, mother, husband, wife, child, guardian, next of kin, domestic partner under ch. 770, or in the absence of any of the foregoing, a friend, or a person charged by law with the responsibility for burial. If 2 or more such persons assume custody of the body, the consent of one of them shall be deemed sufficient.