Quarter of FBI agents assigned to immigration enforcement

The large number of reassignments — about 3,000 agents — reflect a vast reshaping of the nation’s premier law enforcement agency, which has focused on national security threats since the Sept. 11, 2001, terrorist attacks. The intense focus on immigration has raised alarm among current and former FBI agents who say morale is low across the bureau as agents have less time to dedicate to the often complex cases they were hired to work on…