"The time series in question are monthly data from 1960-2004, for over 17,000 police departments, for seven crime types (murder, rape, robbery, aggravated assault, burglary, larceny, vehicle theft), as well as their sum (the so-called Crime Index), and an additional 19 subcategories – e.g., robbery with a gun, knife, personal weapons (hands, feet, etc.), or other; attempted rape; auto, truck or bus, or other vehicle theft...The data consist of monthly counts of these crimes reported by police departments throughout the country to the FBI as part of its Uniform Crime Reporting (UCR) Program."
The data are being made available by Michael Maltz, at Ohio State's Criminal Justice Research Center. Get them at http://sociology.osu.edu/mdm/UCR1960-2004.zip. Maltz also makes some great points about the reliability and validity of self-reported crime data; go check it out.