Pinkerton

Pinkerton is an American private investigation agency and security company established around 1850 in the United States by Scottish-born American cooper Allan Pinkerton and Chicago attorney Edward Rucker as the North-Western Police Agency, which later became Pinkerton & Co. and finally the Pinkerton National Detective Agency. At the height of its power from the 1870s to the 1890s, it was the largest private law enforcement organization in the world. It is currently a subsidiary of Swedish-based Securitas AB.
Pinkerton became famous when he claimed to have foiled the Baltimore Plot to assassinate President-elect Abraham Lincoln in 1861.