Sources have told the Journal Sentinel that the probe, which initially looked at campaign activity by Walker staffers, has moved in a number of directions since then.
This September, a dozen FBI agents and other law enforcement officials raided the Madison home of Cindy Archer, a key Walker aide at the county and the state. Archer has maintained that she did not campaign on work time.
Earlier, immunity was given to Cullen Werwie, Walker’s current spokesman and a former campaign aide, and Rose Ann Dieck, a Republican operative.
Chris Schrimpf, another Walker spokesman, declined to comment Wednesday. Walker, a preacher’s son, has said that he is not concerned about the investigation because he has followed the high standards given to him by his parents.