Wis. Stat. § 968.03: Dismissal or withdrawal of complaints.

(1) If the judge does not find probable cause to believe that an offense has been committed or that the accused has committed it, the judge shall endorse such finding on the complaint and file the complaint with the clerk.

(2) An unserved warrant or summons shall, at the request of the district attorney, be returned to the judge who may dismiss the action. Such request shall be in writing, it shall state the reasons therefor in writing and shall be filed with the clerk.

(3) The dismissals in subs. (1) and (2) are without prejudice.