Schmitz’s lawyer said in the filing the investigation “is about a candidate and his personal campaign committee failing to disclose the funding of such coordinated advocacy.”

That document also includes excerpts from emails between Walker aides and associates that prosecutors say are evidence of state campaign finance violations.

“As the governor discussed … he wants all the issue advocacy efforts to run thru one group to ensure correct messaging,” fundraiser Kate Doner wrote to Walker adviser R.J. Johnson — also an adviser to Club for Growth — in an April 28, 2011, email. “The Governor is encouraging all to invest in the Wisconsin Club for Growth. Wisconsin Club for Growth can accept Corporate and Personal donations without limitations and no donors disclosure.”

State law prohibits campaigns from coordinating their actions with independent groups for political purposes, but it’s less clear whether they can coordinate their work with issue advocacy organizations, which don’t expressly advocate a candidate’s election or defeat.

Prosecutors and the Government Accountability Board argued the coordination turned the Club for Growth’s issue advocacy into express advocacy, but a federal judge disagreed and halted the investigation.