Kate Warne, Detective

Kate Warne: America's First Female Detective, Pinkerton Agency > . 

Kate Warne (1833 – January 28, 1868) was the first female detective, from 1856 to 1868 (her death), in the Pinkerton Detective Agency and the United States.

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Warne reported back to Pinkerton about all her work when he was away from the office and they worked together, on numerous cases, during their tenure. Pinkerton constantly showed a deep trust in the work that Warne performed and acknowledges so in his memoirs. She was in charge of the Female Detective Bureau established by Pinkerton, her title being Supervisor of Women Agents.

https://en.wikipedia.org/wiki/Kate_Warne