A mug shot is an identifying photograph used by law enforcement. These photographs are usually taken after an arrest and entered into a database. They date back to the 19th century, and some sources credit the infamous photographs of the conspirators involved in the murder of the United States' President Abraham Lincoln as beginning the practice of criminal photograph identification.
Often, famed and notorious detective Allan Pinkerton is credited with creating the first mug shot databases. Pinkerton, though hardly a man of unblemished reputation, is nonetheless often cited as the father of modern investigative procedure, including the use of shared databases for identification purposes. Pinkerton was said to be inspired by the photographs of the Lincoln conspirators when implementing his system of mug shot use in the 1860s. Earlier inspiration may also be attributed to artist renditions of fugitive criminals, also known as “wanted” posters, that were popular in the days before photography. These images served to put both civilians and law enforcement agents on the look out for a fugitive in the area.
Until the advent of computers and digital cameras, a mug shot was taken with the arrested person holding a card that bore his or her name and a reference number. Today, that data is generally inserted by digital technology. Whereas the photo would originally be stored in physical filing systems, most identification systems today run entirely through computer databases. Shared databases can help law enforcement co-ordinate efforts, ensuring that a person with other warrants when arrested will be quickly identified.
A mug shot is generally composed of two pictures: a front view and a profile image. These images were once used to create rogues galleries, which are bulletin boards covered with the photos of wanted criminals, used to remind law enforcement officials of primary targets. In many regions, they are public domain images and can be published freely in publications or online. In most cases, any mug shot of any person can be obtained as long as the criminal proceedings have not been sealed by a judge.
Some judges and regions do not permit the use of an identifying mug shot as part of a trial presentation. According to some rulings, this is because juries may have an automatic negative association with these familiar pictures, which may call up prejudicial visions of Old West “wanted” posters and other criminal images. A mug shot is only meant as a record of an arrest, and does not mean that a person has been charged or convicted of any sort of crime.