Examining and expanding the friction ridge value decision

Abstract

The first step of a friction ridge examination involves determining the suitability-or value-of an impression. Often, this is interpreted as whether the impression is suitable for comparison. However, examiners tend to be variable in their suitability determinations, and suitability itself can be a multi-faceted decision, comprising suitability for comparison, suitability for exclusion, suitability for identification, suitability for AFIS entry, complexity, and others. We undertook a white box study to explore the different facets of suitability determinations and to measure the specific categories of information upon which examiners most heavily rely when reaching these decisions. Although minutiae count was the best indicator of a value determination, clarity and distortion were better predictors of complexity determinations. Examiners were found to be highly variable in their determinations, as well as in their annotations of what information they relied upon. Some unanimous decisions were reached for only high-quality impressions; there was never unanimity on "no value" determinations. Examiners tended to use high-confidence minutiae markers, even when there was connective ambiguity or low clarity. Several new suitability categorizations were introduced and had good usage from study participants, indicating that they might have some value for inclusion in routine casework.