The story is vivid and has the quality of a perfect crime narrative: elegant, self-contained, and difficult to disprove. It is also based entirely on a posthumous claim by Decker, who said Valfierno had confided in him before his death. There is no independent documentation, no corroborating testimony, no financial record of the alleged sales, and no evidence that Valfierno existed in the form the story describes. The major scholarship on the theft treats the Valfierno story as unverifiable and not established. As instructed by the guardrails on this article, it is noted here as a theory without documentary support, not as a credible alternative account.
By December 1912 — more than a year after the theft — the Louvre hung a Raphael portrait in the empty space where the Mona Lisa had been. The painting was considered lost. The case had stalled.
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## A Portrait’s History Before the Crime
Understanding the full significance of the theft requires looking at how the Mona Lisa came to be in France in the first place — a provenance history that Vincenzo Peruggia would later misrepresent in ways that shaped public sympathy for his case.
Leonardo da Vinci began work on the painting sometime around 1503. The sitter is widely believed by scholars to be Lisa Gherardini, the wife of a Florentine merchant named Francesco del Giocondo — which is the source of one of its names, *La Gioconda* (or *La Joconde* in French). This identification is not confirmed by any surviving commission document, however, and her identity has been the subject of ongoing historical debate. Leonardo worked on the painting over an extended period that may have continued until as late as 1519.