MADISON, Wis.—Two attorneys have filed motions seeking to stay a secret investigation that reportedly involves Gov. Scott Walker’s campaign and conservative groups.

Online court records don’t explicitly say what the investigation involves. But the filings name Eau Claire County reserve Judge Gregory Peterson and Francis Schmitz as respondents.

Peterson is overseeing an investigation that is reportedly focused on Republican Gov. Scott Walker’s campaign and conservative groups. Schmitz, a Waukesha attorney and a former federal prosecutor, is working on that probe as a special prosecutor.

Attorneys Dean Strang and Matthew O’Neill filed motions with the state appeals court on Thursday on behalf of three unnamed petitioners seeking to suspend a so-called John Doe probe in Milwaukee, Iowa, Dodge, Dane and Columbia counties. They also filed a motion suggesting the requests be sent directly to the state Supreme Court, where conservative justices hold four of the seven seats.

The attorneys also filed a motion to seal documents supporting their motions. Strang declined to comment. O’Neill didn’t immediately return a message. Schmitz and Peterson both declined comment.

Milwaukee County prosecutors in February wrapped up a so-called John Doe investigation into Walker’s associates when he served as Milwaukee County executive. John Doe probes are essentially the state equivalent of a federal grand jury probe.

The investigation led to six criminal convictions. Walker himself was never charged with any wrongdoing.

The Milwaukee Journal Sentinel reported last month prosecutors have launched another John Doe probe. The Wall Street Journal reported last week that investigation is focusing on Walker’s campaign and about 30 conservative groups. Schmitz’s subpoenas have sought records and fundraising information related to a series of recall attempts in 2011 and 2012 that targeted Walker and Republican state senators.

Walker’s state spokesman, Tom Evenson, referred questions to the governor’s campaign. Campaign spokesman Jonathan Wetzel didn’t immediately return telephone and email messages.