Four men in 1940s-style suits and fedoras stand together in a hallway beneath a sign that reads 'ROBBERY'.

Inside the Los Angeles Police Museum sits a collection of worn photo albums that once served as one of the LAPD’s most valuable crime-fighting tools. Filled with mugshots, notes, aliases, and criminal networks, these “mug books” belonged to the department’s legendary Hat Squad, an elite unit created in 1946 to keep organized crime from taking over Los Angeles.

Our regular contributor, Ashley Hlebinsky, shares another installment of our ongoing Display Cases series, exploring how a handful of battered photo albums reveal the rise of postwar organized crime, the controversial tactics of the LAPD’s original Gangster Squad, and the evolution of modern policing.