WASHINGTON — U.S. prosecutors have opened an inquiry into Federal Reserve Chair Jerome Powell, prompting his rare rebuke against escalating pressure from President Donald Trump's administration — and sharp criticism from former leaders of the central bank. In an extraordinary statement released in text and video Sunday, Powell took aim at the Trump administration's "unprecedented action," saying the Fed received grand jury subpoenas and threats of a criminal indictment relating to his Senate testimony in June. The issue at hand was a $2.5 billion renovation of Fed headquarters, which Trump has repeatedly attacked Powell over. Last year, the president floated the possibility of firing Powell over cost overruns for the historic buildings' facelift. Powell dismissed the renovation and testimony as "pretexts." "The threat of criminal charges is a consequence of the Federal Reserve setting interest rates based on our best assessment of what will serve the public, rather than following the preferences of the president," he said. He vowed to carry out his duties "without political fear or fa