Who was the Pinkerton Detective Agency's first female detective?

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

Warne's arguments for joining the detective agency swayed Allan Pinkerton, who employed Warne as the first female detective. Pinkerton soon had a chance to put Warne to the test. In 1858, Warne was involved in the case of Adams Express Company embezzlements, where she was successfully able to bring herself into the confidence of the wife of the prime suspect, Mr. Maroney. She thereby acquired valuable evidence leading to the husband's conviction. Mr. Maroney was an expressman living in Montgomery, Alabama. The Maroneys stole $50,000 from the Adams Express Company. With Warne’s help, $39,515 was returned. Mr. Maroney was convicted and sentenced to ten years in Montgomery, Alabama. In 1860, Allan Pinkerton put Warne in charge of his new Female Detective Bureau.