In 1884, Olney decided to act against Marm Mandelbaum,[1] a criminal fence to many of the street gangs and criminals of New York's underworld. Instead of relying on the city’s police force, which Mandelbaum had reportedly been bribing for decades, Olney hired the Pinkerton Detective Agency, to conduct a sting operation that led to her arrest.[2] The use of Pinkerton detectives caused some friction between the district attorney’s office and the city’s police inspector.[2]
From 1897 until his death, he practiced law as senior partner of the firm of Olney & Comstock. From 1898 on he was also a U.S. Referee in Bankruptcy. In 1919, he was appointed by Surrogate Fowler as referee to investigate claims against the estate of the deceased actress Anna Held.
^Holub, Rona. "Fredericka Mandelbaum." In Immigrant Entrepreneurship: German-American Business Biographies, 1720 to the Present, vol. 2, edited by William J. Hausman. German Historical Institute. Last modified October 15, 2013.