A year ago, in a bureaucratic shift that went unremarked in the somnolent days before Michael Brown was shot dead in Ferguson, Missouri, the US government admitted a disturbing failure. The top crime-data experts in Washington had determined that they could not properly count how many Americans die each year at the hands of police. For the better part of a decade, a specialized team of statisticians within the US Bureau of Justice Statistics (BJS)... had been collecting data [on] any death, of anyone, that happened in the presence of a local or state law enforcement officer. In March of last year, the bureau pulled the plug on the project. As revelations about patterns of abuse in Ferguson and beyond rattle the US criminal justice system from bottom to top, calls for a national police-killings database have once again gained urgency. But an awareness of what has been tried - and failed - remains elusive. A detailed look at what went wrong with the arrest-related deaths count reveals challenges that run deeper than the unwillingness of local police departments to file a report. From 2003 to 2009, plus 2011, the FBI counted an average of 383 "justifiable homicides by law enforcement" each year. The actual number, as estimated by the BJS study, was closer to 928.