Semester

Fall

Date of Graduation

2025

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Forensic and Investigative Science

Committee Chair

Keith Morris

Committee Member

Casper Venter

Committee Member

Tatiana Trejos

Committee Member

Debra Ayers

Abstract

This study investigated the repeatability and reproducibility of minutiae mark-up. The use of fingerprints as a mode of identification has been around for thousands of years with contributions from figures like Sir William Hershel, Thomas Taylor, Henry Faulds, Sir Francis Galton and many more. Latent fingerprint impressions can be deposited by the perpetrator of a crime on a variety of surfaces at a crime scene. Many times, fingerprints are the most widely recovered and used evidence from a crime scene. Once fingerprints are collected, they go through the analysis, comparison, evaluation, and verification (ACE-V) process. This study will focus on the analysis portion of the process. A group of latent fingerprint examiners were recruited to analyze a set of fingerprints. Each examiner marked up the same set of prints on three separate occasions. These mark-ups were done using an automated fingerprint identification system called AFIX Tracker™. The comparison of minutiae was completed by translating the minutiae location information from the summary output of Universal Latent Workstation® (ULW®) by using code in R and RStudio and extracting the x and y coordinates and the rotational angle (theta). The resulting mark-up from each set of prints was then compared to evaluate examiner repeatability. Each set of prints was also compared to sets marked by other analysts to account for reproducibility. In theory, these mark-ups should be the same, however, according to study by Swofford et al. about inter and intra examiner variation in the detection of friction ridge skin minutiae, due to the subjective nature of latent print examination, the detection and interpretation of minutiae are often susceptible to variation. This variation could emerge from variations in eyesight, training, experience, feature selection strategy, potential bias, cognitive style, department procedures, etc. In a study about cognitive issues in fingerprint analysis, Dror et al. noted that examiners have a varying range of consistency among themselves and are inconsistent with other examiners. They also found that these inconsistencies not only vary between examiners but also depend on the nature of the latent print itself. The results of this study showed that the repeatability of the mark-up ranged from -1.5 to 1.5 standard deviations. The reproducibility mark-up ranged from -3 to 3 standard deviations. The study also quantified the latents by high, medium and low quality. Surprisingly, this data indicated that low quality print mark-ups are more reproducible. This could be due to the low minutiae count associated with low quality prints. The overall reproducibility of this study was 97%. Ulery et al. completed a study on inter examiner variation of minutia markup on latent fingerprints and reported an overall reproducibility of 63% (1). This is a difference of 34% which could be due to the types of latents used in each study. Ulery and collaborators used latents that are more similar to casework prints whereas this study used controlled method of gathering latents.

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