Behind the scenes, a top department official pressed employees to gather a list of activists and investigate them, people familiar with the matter said.A top Trump appointee in the Justice Department ordered an aggressive investigation in the last several months of student protesters at Columbia University, raising anger and alarm among career prosecutors and investigators who saw the demand as politically motivated and lacking legal merit, people familiar with the episode said. The demand for the inquiry into students who protested Israel’s conduct of the conflict in Gaza also prompted pushback from a federal magistrate judge, who believed some of...