The U.S. Supreme Court declined Monday to reopen a long-stalled investigation into Wisconsin Gov. Scott Walker's 2012 campaign against a recall effort, permanently ending a probe that had dogged the Republican even as he launched a brief presidential bid last year.

The state's elections board and the Wisconsin Club for Growth say they've reached a settlement over a lawsuit related to an investigation into Gov. Scott Walker's 2012 recall campaign.

A federal appellate panel ruled Monday that a judge had the authority to issue a preliminary order halting a secret investigation into Republican Gov. Scott Walker and other conservative groups.

Court filings made public Wednesday related to the John Doe investigation into Gov. Scott Walker's recall campaign and conservative groups show prosecutors sought to keep the probe secret to avoid publicity, which they feared could hinder or taint their work.

A federal judge's order to stop a John Doe investigation into whether some conservative organizations illegally coordinated campaign financing with Gov. Scott Walker's recall election campaign in 2011 and 2012 has puzzled some in the legal community.

A convoluted legal fight over an investigation that has dogged Wisconsin Gov. Scott Walker for years shows no signs of ending soon, despite a pair of legal wins this week for the first-term Republican who is weighing a presidential run.

Prosecutors investigating Gov. Scott Walker's 2012 recall campaign and conservative groups that supported him won a victory Wednesday with a federal appeals court ruling that, at least for now, blocks a judge's ruling that halted the probe.

A federal judge on Tuesday blocked a secret investigation into possible illegal coordination between conservative groups and recent recall campaigns in Wisconsin, including the 2012 effort to oust Republican Gov. Scott Walker.

The Wisconsin Supreme Court should stay out of a dispute over subpoenas in a secret investigation into possible illegal coordination between conservative organizations and recent recall campaigns, a liberal group said Monday.

A federal judge in Milwaukee says a lawsuit seeking to stop a secret investigation into possible illegal coordination between conservative groups and recent recall campaigns can continue.