The videotaped killing of a black suspect in Baton Rouge by police officers will be the focus of a civil rights investigation by the U.S. Justice Department. Authorities say that 37-year-old Alton Sterling had a gun as he wrestled with police on the pavement outside a convenience store. Police had responded to an anonymous caller who said a man selling homemade CDs was threatening someone with a gun outside the store. But a cell phone video of the Tuesday shooting doesn’t appear to show a gun.