The strategy is demonstrated for fingerprints on stainless steel, chosen in view of its widespread use in common objects (handles, tools, knives) of forensic relevance, onto which is electrochemi- cally deposited an electrochromic polyaniline film. Polyaniline was selected on the basis of the facility to operate in aqueous media, its exceptional stability to redox cycling, and the possibility of electrochemically accessing multiple optically distinct oxidation states.11,12 The participation of both proton (cation) and anion transfers13 to maintain electroneutrality upon changing polymer charge state ensures rapid switching in aqueous media. These attributes have prompted application in electrochromic devices12 in which the goal is the opposite of that here, namely, laterally uniform coloration of the surface, be it an element of a display device14 or an architectural glazing unit.