Federal investigators are trying to determine if former presidential candidate Michele Bachmann’s campaign staff coordinated strategy with an outside “super PAC” in violation of federal law.

The inquiry is the latest in a series of ethics probes into the Minnesota congresswoman’s 2012 Republican campaign, reports The New York Times, which reviewed a grand jury subpoena issued in the case.

Last week, the Department of Justice demanded records from the National Fiscal Conservative PAC, including reports on its finances and its communications with Bachmann, her husband Marcus Bachmann, and former staff members.

According to the Times, federal authorities appear to be pursuing a complaint from former Bachmann campaign staff member Peter Waldron to the Federal Election Commission and the FBI. In his complaint, Waldron said he overheard the president of the PAC ask Bachmann senior advisor Brett O’Donnell about buying ads on Des Moines radio and TV stations before the Jan. 3, 2012 Iowa caucus.

If it turns out the PAC coordinated the ad buys with the campaign it would be in violation of federal election law under some criteria, according to Paul S. Ryan, the senior counsel at the Independent Campaign Legal Center.