Horrall and Assistant Chief Joe Reed resigned in 1949 under threat of a grand jury investigation related to the Brenda Allen scandal. Several of Horrall and Reed's more enduring actions, among others, were to approve a radio show about the LAPD titled "Dragnet" in the same year, with Jack Webb starring in the program, and the 1946 founding of the LAPD's secret "Gangster Squad" aimed to stop the rising threat of the American Mafia and organized crime (led by the local Los Angeles crime family) in the city.