"They found his credentials and his...hat..we think, near what we assume was...him at one time, sir."
"At one time?"
"Formerly, yes. He seemed to have been extensively....gnawed, sir."
Mr. Able of the Able workshop, the alter ego of artist Julian DiMarco, brings us this vintage Pinkerton badge and ID. The badge is all metal, and the agent identification card is based on an example from 1930. The case is 100% antique leather.
The Pinkerton National Detective Agency was at one time the largest security and investigative service in the world. In the decades after its founding in 1850 it became famous both for the quality of its detective services and its involvement in the brutal repression of the American labor movement. In the classic era of the Mythos it was still an immensely powerful organization, but the backlash against its anti-union involvement and the development of professional policing would reduce it to a glorified security and bodyguard company by the 1950s.
Wikipedia has more information about the Pinkerton Agency and its founder, Allan Pinkerton.