"Senior executives are being pushed out and the director, Kash Patel, is more freely using polygraph tests to tamp down on news leaks about leadership decisions and behavior"Behind the scenes, his vision of an F.B.I. under President Trump is quietly taking shape. Agents have been forced out. Others have been demoted or put on leave with no explanation. And in an effort to hunt down the sources of news leaks, Mr. Patel is forcing employees to take polygraph tests.Taken together, the moves are causing worrisome upheaval at the F.B.I., eliciting fear and uncertainty as Mr. Patel and his deputy, Dan...