MADISON, Wis. (AP) — Wisconsin Gov. Scott Walker, a potential 2016 Republican presidential candidate, took part in a nationwide criminal scheme to coordinate fundraising with conservative groups, prosecutors said in court documents unsealed Thursday. No charges have been filed against Walker or any member of his staff. The documents were filed in December as part of an investigation into alleged illegal fundraising and campaign coordination by Walker and his campaign, the Wisconsin Club for Growth, the state Chamber of Commerce and other groups.