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## The Detective Work That Almost Worked
One of the more instructive aspects of the Mona Lisa investigation is how close it came to succeeding in the first weeks — and why it failed despite that proximity.
The investigative team assembled after the theft’s discovery on August 22, 1911, was substantial. Sixty detectives, by most accounts, were involved in the initial stages of the investigation. The examining magistrate system of French justice gave investigators significant powers to question witnesses and compel testimony. The resources of the Sûreté were directed at the case with a seriousness that reflected the crime’s national significance.
The physical evidence was real and potentially productive. The glass case and wooden frame, found in the service stairway, were tangible objects that told investigators how the theft had been executed: the painting had been removed from its case in the building, suggesting the thief knew the case’s construction and was comfortable working with it. The single fingerprint on the glass was a potential identification tool. The locked door and the testimony of the plumber Sauvet established the route of exit and confirmed the approximate timeframe.
The list of workers who had been in the museum on the maintenance day before the theft gave investigators a manageable set of names to investigate. Peruggia’s name was on that list. His prior arrest record existed in the files. His fingerprints had been taken.
The administrative failure that prevented the connection was not dramatically complicated. It was the kind of bureaucratic gap that investigators of that era routinely encountered: a name appearing in slightly different forms in different records, a comparison that required human review and cross-referencing across separate filing systems, a workload that made exhaustive checking difficult. The Bertillon system gave French police excellent records of physical measurements but less systematically organized fingerprint comparison capabilities than some other police forces of the period.