As North Charleston surged in population and popularity last decade, the South Carolina city also grappled with a surge in crime. Leaders came up with a simple policing solution — be aggressive. Police used computers to track the neighborhoods where crime was increasing, then sent waves of officers to patrol and conduct traffic stops.

By the numbers, it worked. Homicides dropped 50 percent, robberies fell 66 percent and rapes 32 percent from 2007 to 2012.

But the police department lost respect with many black residents in the neighborhoods they blitzed. Some began calling friends on their cellphones when they got pulled over and leaving the line open so there could be a witness in case anything happened.

Civil rights leaders now demand a full Justice Department investigation of the force.