As a Colorado peace officer, David J. Cook brought more than 3,000 outlaws to justice and built his reputation on getting results.
Cook worked as a counterespionage agent for the Union Army during the Civil War, tracking down Confederate spies, and investigating various crimes, including gold smuggling.
Opens Detective Agency
The experience made him a natural for law enforcement work and, after the war, opened the Rocky Mountain Detective Association, based in Denver–a group of law enforcement officers which operated throughout the region for 35 years.
During the 1870s, Cook served as city marshal of Denver, Arapahoe County Sheriff, and general of the Colorado militia.
Considered fearless, Cook was an expert horseman and crack shot with both rile and handgun.
Cook, however, had a bit of literary talent, as well, and decided his experiences as a lawman could help others who never held such a post.
Publishes Handbook and Memoir
There was no formal training, or standards, available for a position in law enforcement in the developing west. Anyone who got the job of sheriff or marshal pretty much made up things as they went along.
In 1882, Cook published a memoir, Hands Up! or Twenty Years of Detective Work in the Mountains and on the Plains.
He either wrote it himself, although rumors existed that he had the help of a ghostwriter.
In the book, he created a set of basic rules called Self Preservation for inexperienced Western peace officers.
Cook never struck anyone without a reason, according to various historical accounts.
At the same time, never hesitated to kill, unless the situation demanded.