Steven Biskupic is one of the attorneys named in a state appeals court order, the Wisconsin State Journal reported Friday.
The order issued Thursday by 4th District Court of Appeals Judge Brian Blanchard also reveals that eight unnamed parties are a subject of the secret probe that's reportedly focusing on activities during recall elections in 2011 and 2012, including the one targeting Walker.
The order indicates that Francis Schmitz, the prosecutor in the secret John Doe case, is asking the appeals court to overturn a ruling in January to quash subpoenas and order the return of property to the probe's targets.
The Wall Street Journal reported that the judge ruled some of the subpoenas don't show any probable cause that the targets committed any violations of campaign finance laws. His actual ruling remains under seal.
The Wall Street Journal said it had obtained a copy of the sealed subpoena and the judge's order quashing it. The newspaper previously reported that Walker's campaign, Wisconsin Manufacturers & Commerce, the Wisconsin Club for Growth, and Citizens for a Strong America, their officers and directors had been subpoenaed.
In its last campaign finance statement, Friends of Scott Walker reported paying Biskupic's firm $86,000 in legal fees. Asked earlier this month whether the payments were related to the John Doe probe, the governor responded, "I'm not getting into the details of it."
Biskupic is the former U.S. attorney for the Eastern District of Wisconsin.
There are at least four court cases related to the secret investigation. The Club for Growth and its director Eric O'Keefe filed a federal lawsuit on Feb. 10 arguing that the investigation violates their rights to freedom of speech and equal protection under the law.
There are also two separate cases before the state Supreme Court attempting to stop the investigation, in addition to the appeal Schmitz brought that the appeals court issued its order on Thursday.