 Pinkerton first became interested in criminal detective work while wandering through the wooded groves around Dundee, looking for trees to make barrel staves, when he came across a band of counterfeiters, who may have been affiliated with the notorious Banditti of the Prairie.After observing their movements for some time he informed the local sheriff, who arrested them.This later led to Pinkerton being appointed, in 1849, as the first police detective in Chicago, Cook County, Illinois.