A judge has granted special immunity to the 12th witness in the ongoing John Doe investigation of former employees who served under Gov. Scott Walker when he was Milwaukee County executive.

The Associated Press reported that former Milwaukee municipal judge and private attorney David Halbrooks received immunity in the probe after requesting it from authorities investigating Walker staff members who allegedly worked on his campaign while in the county office.

The investigation has led to the charges against five people who worked under Walker or were associated with his office. One has pleaded guilty to the charges.

Common Cause in Wisconsin Executive Director Jay Heck said he was surprised to see Halbrooks was involved in the case. Heck described Halbrooks as a “Democrat pitbull” and a partisan chair of the State Elections Board, which used to run state elections before the creation of the Government Accountability Board.

“This shows the investigation is very much alive,” Heck said.

He added Halbrooks may have been appointed to the election board by former Senate Majority Leader Chuck Chvala, D-Madison, who served jail time after he used his office staff to further his own political campaign.

Heck also said Walker’s legal defense fund suggests he is either a subject of the investigation or facing criminal changes, since these are the only conditions under which a person can form a legal defense fund under state law.

Erik Kirkstein, political director for United Wisconsin, one of the groups that led the effort to collect signatures to trigger Walker’s recall, said in an email to The Badger Herald Wisconsinites “are ready for some answers.”

“The silence from Scott Walker is deafening,” Kirkstein said. “Wisconsinites have no tolerance for corruption, and there is no doubt that voters will have this John Doe investigation on their minds come the June 5 election.”

Walker’s campaign did not return requests for comment.

University of Wisconsin political science professor Donald Downs, who is also an advisor to the board of directors of The Badger Herald, said the implications of the probe will most likely not be good for the Walker administration. However, he said people have raised concerns the probe may be politically motivated.

The Associated Press contributed to this story.