The Department of Justice will likely convene a grand jury to investigate a leak of evidence collected during a secret criminal investigation into whether Gov. Scott Walker’s recall campaign circumvented state campaign finance law, Attorney General Brad Schimel said Thursday.

“This isn’t the type of investigation that you go knocking on doors and ask people to talk with you,” Schimel said in an interview with the Wisconsin State Journal. “(The investigation is) going to be best suited (in) a protected environment of a courtroom where we’re asking questions and developing information.”

The grand jury would investigate a leak of materials to the Guardian US, an arm of the British newspaper, which published hundreds of leaked documents from a closed secretive John Doe investigation looking into Walker raising millions of dollars for a supposedly independent group to help win the 2011 and 2012 recalls….

Schimel said he won’t investigate a leak of materials to other publications, including the Wall Street Journal’s conservative editorial page.