Wis. Stat. § 708.07: Satisfaction of state mortgages.

In any case where the records of the offices of the state treasurer and secretary of state fail to show any payments made upon any mortgage of real estate to the state or territory of Wisconsin since January 1, 1865, it shall be the duty of the state treasurer, on demand, to execute, acknowledge and deliver to the owner of all or any portion of the land conveyed by any such mortgage a satisfaction in due form of law acknowledging the satisfaction and discharge of such mortgage, and such satisfaction when so executed shall be conclusive evidence of the payment and discharge of such mortgage and the satisfaction of the lien thereby secured.