A small number of police officers are assigned to special work such as accident prevention. Some investigate robberies, homicides, and other crimes. Others are experts in chemical and microscopic analysis, firearms identification, and handwriting and fingerprint identification. In very large cities, a few police officers may work with special units such as mounted and motorcycle police, harbor patrols, helicopter patrols, canine corps, mobile rescue teams, and youth aid services. At regular intervals, police officers report to police headquarters from call boxes, radios, and telephones.
Police officers write reports and maintain police records.
They may be called upon to testify in court when their arrests result in legal action. Candidates must be U.S. citizens, usually at least 20 years of age, and must meet rigorous physical and personal qualifications. Applicants must meet certain standards which vary from state to state. In large police departments, where most jobs are found, applicants usually must have a high school education. An increasing number of cities and states require some college training, and some hire law enforcement students as police interns.