ST. LOUIS • Federal, state and local agencies license police officers to kill, if necessary, but nobody counts all the bodies or tracks what, if any, consequences might follow.

The numbers that do exist are hardly complete.

The nation’s approximately 18,000 police agencies are expected to submit specified categories of crime statistics every year to the FBI’s Uniform Crime Reporting program. But inclusion of justifiable homicides is optional.

A Post-Dispatch analysis of the data from 2005-12 shows more than 1,100 departments — or roughly 6 percent of the country’s law enforcement agencies — have reported a killing by an officer or private citizen that is considered justifiable.

Moreover, the federal data do not record how often police face criminal consequences for using deadly force. A police killing that is deemed a murder presumably is just included among the jurisdiction’s other criminal killings.

The Aug. 9 fatal shooting of Michael Brown, who is black, by Ferguson police Officer Darren Wilson, who is white, ignited not only racially charged protests and riots but fresh questions about the frequency of police killings.

The Police Foundation, a nonpartisan national research group, has been among those seeking answers.

“The lack of data is a real problem. It leaves a tremendous void in the evidence that surrounds this public discussion of police use of force,” Jim Bueermann, the foundation president, said in an interview. “And in a void, people fill that with their own narrative based on their own experiences.”