Audit of CPD Assault-Related Crime Statistics

OIG found that the Chicago Police Department (CPD) incorrectly classified 3.1% of 2012 assault-related events contained in incident reports, under the 10% error rate that the FBI states is acceptable for agencies participating in its national reporting program. In addition, CPD’s CompStat reports and the City’s Data Portal accurately reflected the assault-related incidents in CPD’s data warehouse, the Criminal History Record Information System.

OIG also identified significant errors in CPD’s reports to the Illinois Uniform Crime Reporting (I-UCR) program, which feeds into the Federal Bureau of Investigation’s Uniform Crime Reporting (UCR) system:

  • Contrary to I-UCR reporting requirements, CPD failed to count each victim in multiple victim crimes as a separate offense. This resulted in a 24% undercount in victim offenses in the reporting sample OIG examined
  • CPD erroneously excluded certain crimes committed against protected persons, thereby underreporting all aggravated assaults and batteries to the I-UCR program by 5.7% and 3.2% respectively

CPD agreed with OIG’s findings and is reviewing all aggravated assaults and batteries from 2012 and 2013 to ensure the accuracy of its reports to I-UCR. CPD will also provide clearer guidance on multi-victim crime reporting in its Field Reporting Manual and, if needed, will add categories to its classification rules in order to better address I-UCR reporting needs for incidents involving protected persons.