In the nation’s 30 largest cities, nine chiefs have departed this year alone, compared with the previous decade’s average of four per year. Four retired, while three were fired, and another two resigned after the Department of Justice investigated their departments, says the Christian Science Monitor. “I talk to enough chiefs who recognize they’re one incident away from their whole department being put under a huge microscope,” Chuck Wexler of the Police Executive Research Forum told Reuters. “Mayors are reacting quickly. They’re holding police chiefs to a standard we really haven’t seen ever, especially around issues of use of force and community trust.” Few big-city chiefs last more than four years in the role.