MADISON, Wis. (AP) — A Wisconsin district attorney said Thursday that her office is pursuing an investigation into the removal of an absentee ballot drop box by the mayor of Wausau.

Mayor Doug Diny removed the drop box, located outside of City Hall, on Sunday and distributed a picture of himself doing it while wearing worker’s gloves and a hard hat. Diny is a conservative opponent to drop boxes. He insists he did nothing wrong.

The drop box was locked and no ballots were in it. The city clerk notified Marathon County District Attorney Theresa Wetzsteon and she said in an email on Thursday that she is requesting an official investigation with the assistance of the Wisconsin Department of Justice.

Wetzsteon said she was waiting to hear back from DOJ on her request.

A spokesperson for DOJ did not immediately return a message Thursday.

The incident is the latest example in swing state Wisconsin of the fight over whether communities will allow absentee ballot drop boxes. The Wisconsin Supreme Court in July ruled that drop boxes are legal, but left it up to local communities to decide whether to use them.