MADISON, Wis. -

A subpoena has been filed with the court requiring Gov. Scott Walker to testify in the trial of a former Milwaukee County staffer.

Kelly Rindfleisch is accused of using county time to conduct campaign work for a Republican who lost a lieutenant governor race in 2010. Rindfleisch was Walker's deputy chief of staff when he was the Milwaukee County executive.

She's pleaded not guilty to four felony counts of misconduct in office.

The subpoena has been served on Walker's attorney, Michael Steinle, and has been filed with Milwaukee County Judge David Hanscher.

Walker was previously identified by a prosecutor as a potential witness in the Oct. 15 trial. Rindfleisch is one of six Walker associates facing charges that arose from a secret investigation.

"I think you cannot jump to any conclusions because (Walker) has been subpoenaed as a witness, because none of us have read all the police reports. We've read things in the media. We may know some things about the case, but until we all hear the evidence we're not sure what each witness is going to testify to," said Tim Verhoff, a former prosecutor.

The charges against Rindfleisch stem from an ongoing secret John Doe investigation in Milwaukee County. Walker has repeatedly said he is not a target of the investigation, and some are now wondering if more information will come out.

But Verhoff said people shouldn't count on that.

"The judge in this case has said this is not going to be a trial about Gov. Walker, and I believe that the judge will hold the parties to whatever evidence the governor might have to offer strictly as it relates to this case, and not some grander John Doe scheme," Verhoff said.

Charles Franklin, director of the Marquette University Law School poll, said that polling on the seriousness of the John Doe investigation for Walker had gone up and down -- higher when charges were first filed against Walker's associates and lower as information about the investigation waned.

"I think the right point is we don't know what (Walker) will say. We don't know what the attorneys will ask," Franklin said. "It depends on how the testimony goes, how the cases go, what facts have been speculated, that will determine what, if any, political impact there is."

It's not guaranteed that Walker will take the stand. It's the prosecution's burden to prove its criminal case, and Walker is now listed as a witness for the defense. 

Verhoff said the defense may only choose to call the governor to the stand to rebut previous witness testimony or to lay out part of a counter-case the defense plans to present.