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Gov. Scott Walker's chief spokesman has been granted immunity in the ongoing John Doe investigation of the governor's current and former aides, it was learned Friday.

Former Appeals Court Judge Neal Nettesheim, who is overseeing the secret criminal probe, said he had granted immunity to three people, including Cullen Werwie, spokesman for Walker, in this part of the case. A railroad lobbyist and low-ranking Republican official were also given immunity.

Records show Werwie was granted immunity April 14. Werwie joined Walker's campaign after the September primary and stayed on when Walker took office in January. Werwie earns $61,000 per year.

"No comment," Werwie said when reached late Friday.

The governor was not immediately available for comment.

Nettesheim said he also granted immunity to Ken Lucht and Rose Ann Dieck.

Lucht is the manager of community development with Wisconsin & Southern Railroad. His attorney could not be reached late Friday. He received immunity on Jan. 14.

Dieck, a longtime Republican operative, is listed as the chairwoman of the southwest suburban branch of the Milwaukee County Republican Party. She was granted immunity on Dec. 21.

She was a Walker supporter who volunteered for Republican Rep. Jeff Stone in his unsuccessful bid for Milwaukee County executive.

"They're taking away the rights of those who voted for change," Dieck said during an interview with WTMJ-TV (Channel 4) during March protests at Stone's campaign office. "There was an election on November 2nd. The people in the state of Wisconsin said we need change." Dieck's attorney also was not available Friday afternoon.

Nettesheim said grants of immunity are the only part of a John Doe investigation conducted in open court.

"That's about all I can reveal to you," Nettesheim said from his home.

John Doe investigations are secret proceedings in which witnesses can be subpoenaed and compelled to testify under oath about potential criminal matters and are forbidden from talking publicly about the case.