MADISON (WITI) -- A conservative activist has filed a federal lawsuit to stop a secret John Doe investigation -- a probe that has been examining a possible connection between his group and Gov. Scott Walker's campaign.
The 76-page lawsuit was filed in federal court by Eric O'Keefe -- a self-described "political activist" who runs the Wisconsin Club for Growth.
The conservative group is allegedly being investigated by Milwaukee County District Attorney John Chisholm as part of a secret John Doe proceeding, looking into the potentially illegal coordination between conservative political groups and Gov. Scott Walker's campaign during the 2012 recall election.
"It's always interesting in Wisconsin, that's for sure. I'm sure the closer we get to election time, the more interesting it will get," Gov. Walker said.
The lawsuit cites legal precedents that say "investigations, whether on a federal or state level, are capable of encroaching upon the constitutional liberties of individuals," and "impinge" on "freedom of speech."
The lawsuit calls for an end to the investigation.
"Any of that particular stuff, we haven't been involved in, so we'll have to leave it up top those other parties, but that's not something we're directly involved in," Gov. Walker said.
Gov. Walker says his campaign is not involved in the lawsuit and has nothing to hide.
"We've consistently operated within the law and we'll continue to going forward," Gov. Walker said.
The second John Doe investigation has the potential to become a 2014 campaign issue.
"I favor transparency , and I favor a swift and judicious process of making sure we get to the truth," Mary Burke said.
Burke, a Democratic candidate for governor says voters should be concerned about accusations of illegal coordination between outside groups like the Club for Growth and the governor's campaign.
"I think voters have a right to know who they are voting for and whether there are any legal issues surrounding candidates," Burke said.
The first John Doe investigation lasted nearly three years, and ended in 2013. Six people, including three former Gov. Walker aides were convicted of crimes -- but Gov. Walker himself was not charged with any wrongdoing.