Charles Siringo wrote an expose of the American private-detective industry in the late nineteenth century that detailed fraudulent practices and even criminal activity. Born and raised in Texas, Siringo began working as a cowboy at the age of 12. He drove cattle and established a ranch in the Texas Panhandle for East Coast investors but in 1880 ventured into New Mexico with a posse of cowboys to seize the outlaw, Billy the Kid. They were unsuccessful, and Siringo went on to Las Vegas where he gambled with the ranch's money and lost it all. In need of cash, he wrote A Texas Cowboy, or Fifteen Years on the Hurricane Deck of a Spanish Pony, a dime novel that was sold on trains and reportedly went through a million copies.

In 1886, Siringo began working for the Pinkerton Detective Agency, which solved railroad robberies and cattle-rustling crimes. It was also becoming involved in strikebreaking operations: company management would hire the Pinkertons to infiltrate workers' organizations and harass labor activists. Siringo worked for the company over twenty years but was dismayed to learn that his bosses had falsified many reports. He wrote his expose, Pinkerton's Cowboy Detective, around 1908, but the agency successfully blocked its publication. Siringo rewrote some of it to avoid legal problems and published it in 1912 under the title A Cowboy Detective. A 1915 pamphlet, Two Evil Isms: Pinkertonism and Anarchism, revisited the themes in A Cowboy Detective but named the Pinkertons specifically. Siringo died in Hollywood, California, in 1928.