The dime novel detective "Old Sleuth" was the creation of Harlan Halsey, a former director of the Brooklyn Education Board. Halsey's stories first appeared in 1872 in the six-cent weekly Fireside Companion and quickly became a favorite among readers, who enjoyed the author's novel use of Bowery slang. Old Sleuth was not an elderly man as his name suggests, but rather a strong, virile youth whose favorite disguise was that of an aged, bearded man. [In this episode of Old Sleuth from June 7, 1875, the detective dons his favorite disguise to assist three colleagues investigating the case of a missing woman.]
In the 1880s and 1890s, the character Old Sleuth became popular enough to warrant a separate publication of his own, and George Munro began publishing Old Sleuth Library. Rival publishers Beadle and Adams, in an attempt to capitalize on Old Sleuth's growing popularity, began issuing a detective series of their own under the same title. Munro responded by suing Beadle and Adams, and the New York Supreme Court decided in 1889 that Old Sleuth was Munro's exclusive property.