Allan Pinkerton’s Pinkerton National Detective Agency had already been operating for 15 years when the manhunt for John Wilkes Booth began.
The Pinkerton detectives had foiled a plot to assassinate the president in 1861.
Pinkerton thought Secretary William Stanton would hire him to hunt for Booth, but Stanton told Pinkerton he could go after the same reward as all others.
Pinkerton’s agency was back in the headlines in 1866 when it solved a sensational $700,000 robbery.
After that, the Pinkertons became known as anti-union forces. A Pinkerton man infiltrated the Molly Maguires, the first labor union for Pennsylvania’s Irish coal miners. The miners were protesting harsh conditions imposed by the Philadelphia and Reading Railroad, the company that owned the mines.
The Mollies were charged with murder and convicted largely on McParlan’s testimony, because there were no eyewitnesses. They were hanged, but they received a gubernatorial pardon in the 1970s.
In 1892, Pinkerton detectives and state militia members broke a strike against the Carnegie Steel Company.
Union members grew to hate the Pinkertons and call them “pinks” and “pinkies.”
The use of the word “fink” to mean an informer (originating in 1902) and a strikebreaker (originating in the 1920s) probably came from this use of “pink.”
Source: Listening to America by Stuart Berg Flexner