From the 'About Crime in the U.S. (CIUS)' tab: "'Crime in the United States, 2013', presents data tables containing information on the topics listed below. Data users can download Microsoft Excel spreadsheets of the data tables and Adobe PDFs of most of the text. Offenses Known to Law Enforcement--Includes information about violent crime offenses (murder and nonnegligent manslaughter, rape, robbery, and aggravated assault) and property crime offenses (burglary, larceny-theft, motor vehicle theft, and arson). Expanded offense data--Provides additional data that the program collects on the eight offenses. Depending on the offense, these details may include the type of weapon and the type and value of items stolen. For the offense of murder, expanded homicide data include information about murder victims, offenders, and circumstances that are collected as supplemental homicide data. Clearances--Furnishes information about crimes 'solved' either by arrest or exceptional means. Persons Arrested--Provides the number of arrests made by law enforcement and the age, gender, and race of arrestees for the 28 offenses (see Offense Definitions) for which the UCR Program publishes arrest data. Police Employee Data--Supplies information regarding sworn officers and civilian law enforcement personnel."
Federal Bureau of Investigation: http://www.fbi.gov/