Special agent in the context of "Naval Criminal Investigative Service"

Criminal investigation is an applied science that involves the study of facts that are then used to inform criminal trials. A complete criminal investigation can include searching, interviews, interrogations, evidence collection and preservation, and various methods of investigation. Modern-day criminal investigations commonly employ many modern scientific techniques known collectively as forensic science.

Criminal investigation is an ancient science that may have roots as far back as c. 1700 BCE in the writings of the Code of Hammurabi. In the code, it is suggested that both the accuser and the accused had the right to present evidence they collected. In the modern era, criminals investigations are most often done by government police forces. Private investigators are also commonly hired to complete or assist in criminal investigations.

The United States Army Military Police Corps (USAMPC) is the uniformed law enforcement branch of the United States Army. Investigations are conducted by Military Police investigators under the Provost Marshal General's Office or special agents of the United States Army Criminal Investigation Division.

William Mark Felt Sr. (August 17, 1913 – December 18, 2008) was an American law enforcement officer who worked for the Federal Bureau of Investigation (FBI) from 1942 to 1973 and was known for his role in uncovering the Watergate scandal. Felt was an FBI special agent who eventually rose to the position of Deputy Director, the Bureau's second-highest-ranking post. Felt worked in several FBI field offices prior to his promotion to the Bureau's headquarters. In 1980, he was convicted of having violated the civil rights of people thought to be associated with members of the Weather Underground, by ordering FBI agents to break into their homes and search the premises as part of an attempt to prevent bombings. He was ordered to pay a fine, but was pardoned by President Ronald Reagan during his appeal.

In 2005, at age 91, Felt revealed to Vanity Fair magazine that during his tenure as Deputy Director of the FBI he had been the anonymous source known as "Deep Throat", who provided The Washington Post reporters Bob Woodward and Carl Bernstein with critical information about the Watergate scandal, which ultimately led to the resignation of President Richard Nixon in 1974. Woodward, who had long vowed not to reveal Deep Throat's identity while the source was still alive, quickly confirmed Felt's claim. Though Felt's identity as Deep Throat was suspected, including by Nixon himself, it had generally remained a secret for 30 years. Felt finally acknowledged that he was Deep Throat after being persuaded by his daughter to reveal his identity before his death.