A biometric authentication system (100, 200) comprising: a data storage system (120, 220, 250) configured to maintain, for a group of people, biometric data that includes sorted similarity scores, each of the sorted similarity scores being a number and being computed, by using a process that outputs a numeric value that reflects how similar a first image is to a second image, to represent similarity between a corresponding biometric image and a reference image; and a biometric verification system that includes at least one processor (230, 1030), the biometric verification system being configured to: access a biometric image of at least a portion of a person; access the reference image; compute a similarity score that represents similarity between the accessed biometric image and the reference image; search the sorted similarity scores included in the biometric data using the computed similarity score; and output a result based on the search of the sorted similarity scores included in the biometric data using the computed similarity score, wherein the search and output further comprises: - identify a subset of people that are each associated with a similarity score within a threshold of the computed similarity score - access detailed biometric data for the subset of the people - compare the detailed biometric data for the subset of people to detailed biometric data for the accessed biometric image of the person - identify a match based on comparison results. a data storage system (120, 220, 250) configured to maintain, for a group of people, biometric data that includes sorted similarity scores, each of the sorted similarity scores being a number and being computed, by using a process that outputs a numeric value that reflects how similar a first image is to a second image, to represent similarity between a corresponding biometric image and a reference image; and a biometric verification system that includes at least one processor (230, 1030), the biometric verification system being configured to: access a biometric image of at least a portion of a person; access the reference image; compute a similarity score that represents similarity between the accessed biometric image and the reference image; search the sorted similarity scores included in the biometric data using the computed similarity score; and output a result based on the search of the sorted similarity scores included in the biometric data using the computed similarity score, wherein the search and output further comprises: - identify a subset of people that are each associated with a similarity score within a threshold of the computed similarity score - access detailed biometric data for the subset of the people - compare the detailed biometric data for the subset of people to detailed biometric data for the accessed biometric image of the person - identify a match based on comparison results. access a biometric image of at least a portion of a person; access the reference image; compute a similarity score that represents similarity between the accessed biometric image and the reference image; search the sorted similarity scores included in the biometric data using the computed similarity score; and output a result based on the search of the sorted similarity scores included in the biometric data using the computed similarity score, - identify a subset of people that are each associated with a similarity score within a threshold of the computed similarity score - access detailed biometric data for the subset of the people - compare the detailed biometric data for the subset of people to detailed biometric data for the accessed biometric image of the person - identify a match based on comparison results.