In the early days of Johnson County's history, menacing bands of thieves roamed the countryside and stole what were usually a family's most prized possessions: horses. Horses were crucial for farming and transportation, and many families depended on them for their livelihoods. By the late 1850s, horse thievery became an epidemic. In 1859 alone, there were over a dozen horse theft incidents in Shawnee. An investigation revealed that border ruffians from Missouri were entering Kansas territory for the sole purpose of plundering the horse supply in Johnson County and surrounding areas. The thieves were selling many of the horses in the small, guerrilla-friendly town of Papinsville in Bates County, Missouri.
Johnson County residents responded to the crimes by forming "vigilance committees." These committees were common in frontier towns due to the limited role of law enforcement. Vigilance committees often took the law into their own hands and decided the fates of accused thieves. At least five accused horse thieves were hanged from a hickory tree at what is now the corner of 55th Street and Queal Drive in Shawnee. The men were then buried there, and the small plot of land became known as "Horse Thief Cemetery." Today it is known as Campbell Cemetery. Only a set of stairs, a marker and a few posts remain at the site.
Shawnee was not the only Johnson County town to form a vigilance committee. The Central Protective Association (CPA) was founded in Missouri in 1871 specifically to address horse thievery. Citizens formed thirteen CPA chapters in different Johnson County towns.
As the twentieth century progressed and Johnson County developed, the issue of horse thievery mostly disappeared. The CPA, however, remained an important social institution for the community. CPA groups regularly held events and parties. Although the atmosphere changed, CPA members still took their responsibilities seriously. An Olathe Mirror article from 1922 described a CPA picnic in Lenexa that featured a baseball game, races and contests. The article ended, however, with a warning to any potential thieves: "No use to steal any horses or other farm property in the vicinity of Lenexa, for a general call is sent over the telephone, and the leaguers are soon covering all the roads and byways."
- Matt Gilligan, Johnson County Museum