The FBI’s Identification Division, which maintained the national fingerprint repository, would have had records from at least several of these arrest events. By 1934, the Division contained millions of records, and the Henry System classification allowed an examiner to quickly identify which records needed to be pulled for direct comparison against a questioned print.
The specific impressions used in the postmortem comparison — which sets of known prints were examined against the postmortem prints from the morgue — are not fully documented in the accessible record. The memo documenting the comparison exists; the specific methodology of the comparison, beyond the general finding of “unexplained differences” attributable to acid and the positive identification from surviving ridges, is not detailed in available secondary sources.
What is clear is that there was a known record of sufficient quality to support the comparison. Dillinger’s decade-long interaction with the criminal justice system had produced that record. The irony was complete: the same system he had first entered in 1924 when he followed his father’s advice and pled guilty to the Mooresville robbery had generated the documentation that identified his body forty years later when it lay in a Chicago morgue.
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## The Complexity of “Public Enemy Number One”
The designation of John Dillinger as Public Enemy Number One — formally announced on June 22, 1934, his thirty-first birthday — was both a law enforcement statement and a media event.
The term “public enemy” had been used in Chicago crime discourse since the late 1920s, when the Chicago Crime Commission began publishing lists of the most dangerous criminals operating in the city. It entered the broader national vocabulary through movie titles, newspaper usage, and institutional adoption. By 1934, the FBI had incorporated it into its own public communications as a way of designating priority fugitives.