Abstract: A fingerprint matcher links together minutiae from a search print and minutiae from a file print in a chain to determine if the two prints match. Minutiae are extracted from the images of the search and file prints. Geometric and other relationships between close minutiae in each print are calculated. A table of candidate "steps" is formed. Each step consists of four minutiae, two close search minutiae and two close file minutiae. Each "rung" of the step is a search-file pair, the candidate mating of presumed identical minutiae in the two images. Each "riser" of the step is formed by two close minutiae, search minutiae on the one side and file minutiae on the other. A candidate step is entered into the table if and only if the relationships between search minutiae are similar to those between file minutiae. The number of candidate steps is reduced by requiring that each step adhere to various rules regarding the presence of other steps in the table and the identity of minutiae therein.