Librarian Note: There is more than one author by this name in the Goodreads database.
George Thompson (1823-c1873), who also wrote under the pseudonym Greenhorn, was the most prolific author of city mysteries. He was the editor of The Broadway Belle (1855-1858), a sporting paper. Thompson wrote magazine serials, pamphlets, and novels (perhaps as many as sixty). His works include: City Crimes; or, Life in New York and Boston (1849), Venus in Boston (1849), Jack Harold (1850) and Locket: A Romance of New York (1855).
Classic George Thompson City Mystery, meaning: lots of salacious prose and teasing nakedness, but the actual sex is all off stage; the rich bad guys pay for their crimes, while the poor often get off; innocent females have horrible experiences but mostly are rescued before being outright raped; and there are lots of females who're sexually avaricious. City Mysteries were something like the pulps -- the plots are over the top, the prose florid, the characters types rather than rounded individuals, and the appeal is not particularly literary, but rather the author's audaciousness and willingness to break rules, both literary and social.