A device, and a method for its operation, for verifying a person's identity by comparing in a correlator (18) selected features of a reference fingerprint image, generated in a sensor (10) from the fingerprint of a person of known identity, with a subject fingerprint image taken from a person whose identity is to be verified. In an enrollment procedure, a fingerprint from a person of known identity is analyzed in an enrollment processor (14) to locate multiple reference patches that together are distinctive to that person's fingerprint. The reference patch images are stored, together with their locations in the image, in a reference image storage unit (16). When a subject fingerprint image is later provided, every reference patch is compared with every possible patch of similar size in the subject image, to find a set of candidate match locations in the subject image. Then a subset of the candidate match locations is selected such that the candidate match locations in the subset are practically geometrically congruent with the locations of a corresponding subset of reference patches. A verification match is declared based on the number candidate match locations in the selected subset that satisfies this geometric constraint.