Police Technology by Glen Forrest

Author:Glen Forrest
Language: eng
Format: epub
Publisher: Britannica Educational Publishing
Published: 2016-11-23T00:00:00+00:00

Detectives pose with a computer voice-stress analyzer (VSA) at a police department in Pennsylvania. VSAs measure changes in voice patterns that may indicate when a person is lying.

CHAPTER THREE

CRIMINAL IDENTIFICATION

Criminal identification based on various scientific methods has acquired a mythical dimension thanks to popular fictional accounts of police investigation. However, scientific methods of criminal identification are actually more useful for producing evidence to be used in court to secure the conviction of a suspect—typically identified through the traditional investigative method of questioning the witnesses of a crime—than they are for identifying who the perpetrator of a crime is, particularly if the perpetrator has no previous criminal record.

Scientific means of criminal identification can be classified in two categories. The oldest and most traditional means, such as photography and anthropometry, depend initially on the arrest of a suspect, who is then photographed and described physically. These photographs and anthropometric descriptions can be used at a future time to reidentify a criminal, but this person needs to have been caught in a first offense to trigger the system. Newer identification techniques have no such limitations. They do not consist of depictions of a whole individual; rather, they involve the scientific analysis of traces that a perpetrator may leave behind—for example, fingerprints or blood (a source of DNA). The results of such analyses can be matched with the physical characteristics of a suspect who has never been arrested before and thus can result in a new positive identification.

Nevertheless, the few studies of criminal investigation that have been conducted stress the limited contribution of such scientific methods to the identification of unknown perpetrators. The most efficient identification technique—that is, the questioning of witnesses—is also the most time-honored. The probability of solving a crime drops dramatically when there are no witnesses of any kind.

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