A crime can be considered solved, or "cleared", by law enforcement agencies in two basic ways--by arrest or by exceptional means. When a crime is solved by arrest, three conditions must be met: at least one person has been arrested, charged with the offense and turned over to the courts for prosecution. According to the FBI's Uniform Crime Reporting (UCR) Program, the calculation for the clearance rate is based on the number of crimes, not the number of persons arrested. In order to meet the requirements for clearing a crime based on exceptional means, the law enforcement agency must have identified the offender and the offender's location, gathered enough evidence to make a charge and turn the offender over for prosecution, and encountered some circumstance that prevented the offender from being arrested, charged and prosecuted. Examples of those circumstances include the death of the offender or the refusal of the victim to cooperate with the prosecution. The data used for this measure came from a web tool provided by National Public Radio (NPR) based on data compiled from the FBI. Data were available for only ten of the fourteen police departments in the county, but those ten represent over 90 percent of the county's population. The Fulton County Sheriff and university police departments were excluded because those agencies are generally involved in very few arrests or criminal investigations. The percentage of crimes solved is calculated by dividing the number of crimes solved in the year by the number of new crimes in the same year. Since some crimes solved may have occurred in a previous year, the clearance rate in some cases may be over 100 percent. Part 1 crimes include murder and non-negligent homicide, rape, robbery, aggravated assault, burglary, larceny-theft, motor vehicle theft and arson.