Detectives

The United States inherited much of its law enforcement tradition from England. During the early history of the United States, criminal investigation was often handled by bounty hunters, sometimes called stipendiary police or thieftakers. These early detectives were paid a reward or fee by governments, private individuals, or businesses (such as insurance companies) for apprehending suspected criminals or returning stolen property. Many were petty criminals themselves.

The early 19th century saw growing social unrest and criminal activity in the United States as the country moved from an agrarian to an industrialized, urban economy. By the mid-1800s the upsurge in crime led to public calls for greater government action. The first police department in the United States was formed in New York City in 1844. Before long many cities and towns across the country also established organized police forces, including special investigative divisions. The investigation of crimes, however, was still commonly handled by stipendiary police and thieftakers. Although police departments were created with the hope of reducing crime, numerous scandals within their own ranks soon erupted. Corruption within local police departments was a continual problem and by the early 1900s became a motivating cause for police reforms and for the establishment of state police agencies, including state investigative divisions.

Also notable during the 19th century was the growth of private investigative firms. Probably the most famous was the Pinkerton National Detective Agency, formed by Allan Pinkerton in 1850. The agency became famous for its ability to apprehend train robbers, kidnappers, thieves, and forgers. The company's reputation, along with Pinkerton's rejection of rewards in favor of a set daily fee for his agents, helped establish professional standards for detective work. The company, which is now known as Pinkerton Consulting & Investigations, is still in operation today.

The U.S. Secret Service was formed in 1865. Although later associated with the protection of the president and other officials, the secret service was created to investigate counterfeit money. Another federal agency, the Bureau of Investigation (later the Federal Bureau of Investigation, or FBI), was created in 1908 by executive order of President Theodore Roosevelt. It began by investigating criminal activity on government property, crimes by government officials, antitrust cases, and numerous fraudulent schemes.

In the 20th century, the federal government established a number of other investigative agencies. During Prohibition, thousands of detectives were employed by the Treasury Department to enforce the government's ban on alcoholic beverages as well as to investigate the escalating crime surrounding the sale of liquor. Today narcotics squad detectives, employed by the U.S. Drug Enforcement Administration, are charged with a similar duty.

The field of criminal investigation has been revolutionized by advances in technology; the use of fingerprinting for the identification and detection of criminals, for instance, has made a great impact. Fingerprinting began to be widely used by police departments in the early 1900s. Methods of analyzing bloodstains, saliva, and hair and skin traces, as well as precise ways of matching up various inorganic substances, such as paint and cloth fibers, have also aided detectives. More recently, the use of voiceprinting, biometrics, the genetic technique of DNA-printing, and artificial intelligence have shown promise for more sophisticated detection.