President Donald Trump’s Justice Department crossed a new threshold with its criminal investigation of top Democratic elected officials in Minnesota, targeting vocal critics during a moment of crisis in which protesters and federal agents are clashing on icy city streets.The Twin Cities have been a tinderbox for more than a week since an Immigration and Customs Enforcement officer fatally shot a woman in her vehicle, with residents confronting ICE agents. Trump has raised the prospect of sending U.S. troops into the state, and the Justice Department escalated tensions Friday as it prepared to send subpoenas to Gov. Tim Walz and...