The company was formed to be a direct competitor to the Pinkerton Detective Agency, but never achieved this status.
[2] Many of the agents employed by Thiel spied on railroad workers, covering every state and territory in the Union, as well as Canadian provinces between Vancouver Island and Nova Scotia.
They referred to themselves as "testers", meaning that they tested employees' honesty, while railroad workers called them "spotters".
[3][4] One of the company's first employees was John F. Farley, a former United States Cavalry trooper.
[5] By 1914 Farley was assistant general manager of the Thiel Detective Service Company.