Inter and Intra-Examiner Variation in the Detection of Friction Ridge Skin Minutiae

• NCJ Number: 243854
• Journal: Journal of Forensic Identification Volume: 63 Issue: 5 Dated: September - October 2013 Pages: 553-571
• Author(s): Henry Swofford; Shauna Steffan; Garold Warner; Candice Bridge; Jeff Salyards
• Date Published: October 2013
• Length: 19 pages
• Publication Format: Article
• Publication Type: Research (Applied/Empirical)
• Language: English
• Country: United States of America

Annotation

This study examined variations in the detection of friction ridge skin minutiae between inter- and intra-examination.

Abstract

Friction ridge skin minutiae (bifurcations, ridge endings, dots) and their unique arrangements are the primary information detected and evaluated by tenprint and latent print examiners when comparing unknown friction ridge skin impressions to known (record) impressions. During the analysis of friction ridge skin impressions, examiners visually detect and interpret the minutiae available for comparison to the known impression. Because this is a subjective process, the detection and interpretation of minutiae is prone to variation. Whereas earlier studies have demonstrated inter-examiner variation using impressions having a wide range of quality, this study focuses on high-quality impressions to evaluate base-line level of variations that can be expected when detecting and interpreting friction ridge skin minutiae under optimal conditions. The standard deviation (SD) of total minutiae detected fluctuated depending on the image, whereas it was much higher for those impressions bearing breaks in the ridges as a result of creases. When comparing various examiner demographics, many of the observed inter- and intra-examiner variations in the detection of minutiae were to a statistically significant degree (95 percent confidence level). Although the analysis of friction ridge skin minutiae is inherently subjective, variation in the detection of minutiae may not necessarily translate into variation of examiners' conclusions nor should be necessarily considered a limitation of the discipline. Nevertheless, efforts should be made by the discipline to reduce as much variation as possible. Accordingly, these findings suggest that attention should be given towards the creation of standards and guidelines related to defining and selecting minutiae and further emphasize the importance of documenting the specific minutiae and related information detected by examiners during the analysis of friction ridge skin impressions to facilitate greater transparency of the information relied upon to reach a suitability determination or conclusion (identification, exclusion, or inconclusive). (Published Abstract)