Cadaver dog

A police dog, known in some English-speaking countries as a "K-9" or "K9" (a homophone of "canine"), is a dog that is specifically trained to assist police and other law-enforcement personnel. Their duties include: searching for drugs and explosives, locating missing people, finding crime scene evidence, and protecting their handlers. Police dogs must remember several verbal cues and hand gestures. The most commonly used breeds are the German Shepherd, Belgian Malinois and Rottweiler.

In many common law jurisdictions, the intentional injuring or killing of a police dog is a felony.

Dogs have been used in law enforcement since the Middle Ages. Money was then ide in the villages for the upkeep of the parish constable's bloodhounds that were used for hunting down outlaws. In France, dogs were used in the 14th century in St. Malo. Bloodhounds used in Scotland were known as "Slough dogs" - the word "Sleuth", (meaning detective) was derived from this.

The rapid urbanization of London in the 19th century increased public concern regarding growing lawlessness - a problem that was far too great to be dealt with by the existing law enforcement of the time. As a result, private associations were formed to help combat crime. Night watchmen were employed to guard premises, and were provided with firearms and dogs to protect themselves from criminals.

One of the first attempts to use K9s in Policing was in 1869 by the Commissioner of the Metropolitan Police of London, Sir Charles Warren. Warren's repeated failures at identifying and apprehending the serial killer Jack the Ripper had earned him much vilification from the press, including being denounced for not using bloodhounds to track the killer. He soon had two bloodhounds trained for the performance of a simple tracking test from the scene of another of the killer's crimes. The results were far from satisfactory, with one of the hounds biting the Commissioner and both dogs later running off, requiring a police search to find them.

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