Much like the narrative arc of a crime mystery, PFAS “fingerprinting” promises a dramatic resolution to the question “Who did it?” Fingerprinting is often used in the context of contamination “source tracking” and “source attribution.” Fingerprinting analyses include an array of visualization and statistical tools applied to chemical concentration data. These include pie charts, bar charts, radial plots, comparison of concentration ratios, principal component analysis, and correlation matrices. However, fundamental flaws can easily lie beneath visually attractive graphics and statistical plots. For example, chemical signatures can be distorted by how non-detect concentrations values are treated, and by neglecting chemical transport processes that are common to both PFAS and traditional contaminants such as TCE. This presentation will highlight how some kinds of PFAS chemical signature analyses can tell a false story. Fingerprinting can be a useful tool, but it is not a substitute for traditional methods.