Henry C. Lee

In the late 1960s the Federal Bureau of Investigation (FBI) established the Behavioral Science Unit (BSU), the first official department for criminal profiling in the United States. Criminal profiling is the development of an offender description by examining evidence. In 1972 a new FBI academy was opened in Quantico, Virginia, and the BSU became permanently based there. FBI profilers interviewed a number of existing prisoners in order to improve their techniques and better understand the minds of serial offenders. FBI profiler and investigator Robert Ressler published the results of this study in his book Sexual Homicide: Patterns and Motives.

Ressler's book is the main resource investigators use when they encounter a series of murders or sex crimes that appear to be linked. As an agent, Ressler also coauthored the FBI Crime Classification Manual. He coined the term "serial killer" and reported on his own interviews with many elusive murderers in his book entitled Whoever Fights Monsters. Ressler, John Douglas, and others helped develop the art of criminal profiling in the hopes of preventing future crimes and apprehending those who have already committed them.

Criminal profiling has a number of names such as "psychological profiling," "criminal personality profiling," and "behavioral crime scene analysis." The FBI refers to it as "criminal investigative analysis," and its profilers as "mindhunters." Profiling is a technique used to help law enforcement narrow its search when multiple suspects and multiple crimes exist. The offenders are not specifically identified but the major personality and behavioral characteristics of potential suspects are revealed.

Profilers examine crime scenes for clues that could suggest the type of person responsible. Details such as motivation, lifestyle, victim selection, and mental state can be gathered by a good profiler. In addition to physical evidence, profilers use police reports, crime scene photographs, and autopsy reports. Profilers make educated guesses in an investigation, but police agencies decide which evidence to use in solving actual crimes.

In 1984 President Ronald Reagan (1911–2004; served 1981–89) announced the formation of the FBI's National Center for the Analysis of Violent Crime (NCAVC). Its mission is to identify and track serial killers. At the same time the FBI's Violent Criminal Apprehension Program (VICAP) began. It was formed to link serial crimes across jurisdictions using a computer program. Profilers in the twenty-first century are increasingly called upon to investigate international crimes that can include dozens of physical locations and hundreds of individuals.