U.S. independent police force.
The agency was founded in 1850 by Allan Pinkerton (1819–84), former deputy sheriff of Cook county, Ill. It originally specialized in railway theft cases, protecting trains and apprehending train robbers. It solved the $700,000 Adams Express Co. theft in 1856, and in 1861 it thwarted an assassination plot against president-elect Homestead Strike ). It was instrumental in breaking up the Molly Maguires .