U.S. flag

An official website of the United States government, Department of Justice.

Improving the Understanding and the Reliability of the Concept of "Sufficiency" in Friction Ridge Examination

NCJ Number
Date Published
July 2013
97 pages
This project examined the concept of "sufficiency" associated with decisions by latent print examiners at the conclusions of the various phases of the print examination process.
The study resulted in two main findings. First, the concept of "sufficiency" is mainly driven by the number and spatial relationships between the minutiae observed on the latent and control prints. Examiner demographics (training, certification, and years of experience) or non-minutiae features (such as level-three features) did not play a major role in examiners' decisions. Second, there was significant variability between the detection and interpretation of friction-ridge features. This was observed at all levels of detail and for factors that potentially influenced the examination process, such as degradation, distortion, or influence of the background and the development technique. Researchers concluded that standards and training should be developed in order to ensure consistency in the definition, selection, interpretation, and use of observation in examiners' decisions on friction-ridge impressions. The study's methodology involved a Web-based interface designed to capture the observations of 146 latent-print examiner and latent-print trainees on a set of 15 pairs of latent/control prints, as well as examiners' decisions at the end of each phase of the examination process. A statistical model was also developed for quantifying the specificity of the configurations of minutiae annotated on the prints by the participants. Random Forest classifiers were used to measure the importance of variables on the decisions made by the participants. Random Forest classifiers were used as rational proxies for the decisionmaking process of the examiners based on the observations of the latent/control prints. 48 figures, 36-item bibliography, and appended 14 trial photographic images of latent prints

Date Published: July 1, 2013