Once upon a time on patrol

      Between 1930 and 2000, law enforcement agencies across the nation evolved considerably. From the first two-way radio and the organization of gangbusters into a federal, multijurisdictional endeavor, to the use of less-lethal ammunitions and geospatial tracking technology, a cop's job is more techno-centric than ever, though certainly no less dangerous.


   • The single deadliest year in law enforcement history — 282 officers killed.

   • The prototype of the present-day polygraph is developed for use in police stations.

   • IACP's uniform crime records system is turned over to the FBI.


   American police begin the widespread use of the automobile.


   • The FBI inaugurates its crime laboratory which, over the years, comes to be world renowned.


   • Boston Police begin using the two-way radio.


   • Radar is introduced to traffic law enforcement and the American Academy of Forensic Sciences (AAFS) meets for the first time.


   • The last year in United States history in which fewer than 100 police officers were killed in the line of duty; 98 officers made the ultimate sacrifice in 1949.


   • The New Orleans Police Department installs an electronic data processing machine, possibly the first department in the country to do so. The machine is not a computer, but a vacuum-tube operated calculator with a punch-card sorter and collator to summarize arrests and warrants.


   • A former marine invents the side-handle baton, a baton with a handle attached at a 90-degree angle near the gripping end. Its versatility and effectiveness eventually make the side-handle baton standard issue in many U.S. police agencies.


   The first computer-assisted dispatching system is installed in the St. Louis police department.


   • The National Law Enforcement Telecommunications System, a message-switching facility linking all state police computers except Hawaii, is born.


   • Portable two-way radios proliferate in law enforcement agencies.


   • AT&T announces it will establish a special number, 911, for emergency calls to the police, fire and other emergency services.


   • The large-scale computerization of U.S. police departments begins. Major computer-based applications in the 1970s include computer-assisted dispatch (CAD), management information systems, centralized call collection using three-digit phone numbers, and centralized integrated dispatching of police, fire, and medical services for large metropolitan areas.

Mid 1970s

   The National Institute of Justice funds the Newton, Mass., Police Department to assess the suitability of six models of night vision devices for law enforcement use. The study leads to the widespread use of night vision gear by today's police agencies.


   • The National Institute of Justice initiates a project that leads to the development of lightweight, flexible, and comfortable protective body armor for police. It is made from Kevlar, a fabric originally developed to replace steel belting for radial tires.


   • The first electronic stun gun is built after five years of work by NASA researcher Jack Cover.


   • Rockwell International installs the first fingerprint reader at the FBI. In 1979, the Royal Canadian Mounted Police implements the first actual automatic fingerprint identification system (AFIS).


   • Police departments begin implementing "enhanced" 911, which allows dispatchers to see on their computer screens the addresses and telephone numbers from which 911 emergency calls originated.


   • Pepper spray, widely used by the police as a force alternative, is developed. Oleoresin Capsicum (OC) is synthesized from capsaicin, a colorless, crystalline, bitter compound present in hot peppers.


   • Motorola MDT mobile data terminal (only capable of inquiries, not data entry) had to construct duplicate system to enter data.


   Florida and several other locations use satellite technologies to track the exact geographical location of offenders using global positioning systems (GPS). The system consists of 24 military satellites that orbit 11,000 miles above the Earth.


   • The National Law Enforcement Officers Memorial is dedicated in Washington, D.C.


   • Congress enacts CALEA, a program that preserves the ability of law enforcement agencies to conduct electronic surveillance by requiring telecommunications carriers and manufacturers of telecommunications equipment to modify and design their equipment, facilities and services to ensure that they have the necessary surveillance capabilities.


   • More agencies experiment with Geographic information systems (GIS). Computerized crime mapping lets agencies plot crime-related data against a digitized map of a community, city, or region. Crime-related data can then be compared and analyzed with other external data sources.


   • The National Academy of Sciences announces there is no longer any reason to question the reliability of DNA evidence.


   • The Adam Walsh Child Protection and Safety Act of 2006 creates a national sex offender public database, new registration requirements for convicted sex offenders, and a uniform national system for tracking and locating missing or noncompliant sex offenders.


   • Several cities and police departments install wireless video surveillance systems, or expand upon existing systems, to better patrol communities.