Generalization in fingerprint matching experiments

PLoS ONE, 2012

The interpretation of forensic fingerprint evidence relies on the expertise of latent print examiners. We tested latent print examiners on the extent to which they reached consistent decisions. This study assessed intra-examiner repeatability by retesting 72 examiners on comparisons of latent and exemplar fingerprints, after an interval of approximately seven months; each examiner was reassigned 25 image pairs for comparison, out of total pool of 744 image pairs. We compare these repeatability results with reproducibility (inter-examiner) results derived from our previous study. Examiners repeated 89.1% of their individualization decisions, and 90.1% of their exclusion decisions; most of the changed decisions resulted in inconclusive decisions. Repeatability of comparison decisions (individualization, exclusion, inconclusive) was 90.0% for mated pairs, and 85.9% for nonmated pairs. Repeatability and reproducibility were notably lower for comparisons assessed by the examiners as ''difficult'' than for ''easy'' or ''moderate'' comparisons, indicating that examiners' assessments of difficulty may be useful for quality assurance. No false positive errors were repeated (n = 4); 30% of false negative errors were repeated. One percent of latent value decisions were completely reversed (no value even for exclusion vs. of value for individualization). Most of the inter-and intra-examiner variability concerned whether the examiners considered the information available to be sufficient to reach a conclusion; this variability was concentrated on specific image pairs such that repeatability and reproducibility were very high on some comparisons and very low on others. Much of the variability appears to be due to making categorical decisions in borderline cases. Citation: Ulery BT, Hicklin RA, Buscaglia J, Roberts MA (2012) Repeatability and Reproducibility of Decisions by Latent Fingerprint Examiners. PLoS ONE 7(3): e32800.

Forensic Science International, 2020

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PLoS ONE, 2014

Latent print examiners use their expertise to determine whether the information present in a comparison of two fingerprints (or palmprints) is sufficient to conclude that the prints were from the same source (individualization). When fingerprint evidence is presented in court, it is the examiner's determination-not an objective metric-that is presented. This study was designed to ascertain the factors that explain examiners' determinations of sufficiency for individualization. Volunteer latent print examiners (n = 170) were each assigned 22 pairs of latent and exemplar prints for examination, and annotated features, correspondence of features, and clarity. The 320 image pairs were selected specifically to control clarity and quantity of features. The predominant factor differentiating annotations associated with individualization and inconclusive determinations is the count of corresponding minutiae; other factors such as clarity provided minimal additional discriminative value. Examiners' counts of corresponding minutiae were strongly associated with their own determinations; however, due to substantial variation of both annotations and determinations among examiners, one examiner's annotation and determination on a given comparison is a relatively weak predictor of whether another examiner would individualize. The extensive variability in annotations also means that we must treat any individual examiner's minutia counts as interpretations of the (unknowable) information content of the prints: saying ''the prints had N corresponding minutiae marked'' is not the same as ''the prints had N corresponding minutiae.'' More consistency in annotations, which could be achieved through standardization and training, should lead to process improvements and provide greater transparency in casework.

The purpose of the present study was to analyse professional fingerprint examiners' investigative practices in the context of discrepancy decisions concerning challenging latents during fingerprint analysis and identification. The participants were fingerprint experts from the Forensic Laboratory of the Finnish National Bureau of Investigation. The data were from five audio-recorded " discrepancy meetings " where two examiners were discussing the rationale and justification for their differing interpretations of challenging and distorted fingerprint evidence. The meetings were chaired by the quality manager of the fingerprint group, who also in the first author of this article. The research questions addressed were as follows: What does the examiner see in the latent fingerprints? What does the examiner actively do with the latents? How were decisions made during the investigative process? In accordance with Goodwin's professional vision framework, the results revealed how the participants used partial and limited information in making judgments about the difficult and distorted latents. The examiners appeared to be involved in active, constructive efforts, mentally, to repair poor latents by supplementing with missing information. They also highlighted various aspects of latents by colour coding as well as manipulated fingerprint images in several ways so as to make the significant patterns easier to recognize. Because the methods and practices of characterizing latents were only vaguely specified, the examiners used locally developed ad hoc practices to facilitate their investigations, ending up with different interpretations. It is concluded in the article that the fingerprint community in Finland should make strong efforts to develop the methods of fingerprint investigation and determine clearer criteria for decision making and documentation practices. Furthermore, the interpretations made by fingerprint experts should be made more transparent to the customers.

Forensic Science International, 2017

Exclusion is the determination by a latent print examiner that two friction ridge impressions did not originate from the same source. The concept and terminology of exclusion vary among agencies. Much of the literature on latent print examination focuses on individualization, and much less attention has been paid to exclusion. This experimental study assesses the associations between a variety of factors and exclusion determinations. Although erroneous exclusions are more likely to occur on some images and for some examiners, they were widely distributed among images and examiners. Measurable factors found to be associated with exclusion rates include the quality of the latent, value determinations, analysis minutia count, comparison difficulty, and the presence of cores or deltas. An understanding of these associations will help explain the circumstances under which errors are more likely to occur and when determinations are less likely to be reproduced by other examiners; the results should also lead to improved effectiveness and efficiency of training and casework quality assurance. This research is intended to assist examiners in improving the examination process and provide information to the broader community regarding the accuracy, reliability, and implications of exclusion decisions.

Proceedings of the National Academy of Sciences of the United States of America, 2011

The interpretation of forensic fingerprint evidence relies on the expertise of latent print examiners. The National Research Council of the National Academies and the legal and forensic sciences communities have called for research to measure the accuracy and reliability of latent print examiners' decisions, a challenging and complex problem in need of systematic analysis. Our research is focused on the development of empirical approaches to studying this problem. Here, we report on the first large-scale study of the accuracy and reliability of latent print examiners' decisions, in which 169 latent print examiners each compared approximately 100 pairs of latent and exemplar fingerprints from a pool of 744 pairs. The fingerprints were selected to include a range of attributes and quality encountered in forensic casework, and to be comparable to searches of an automated fingerprint identification system containing more than 58 million subjects. This study evaluated examiners o...

Forensic Science International, 2011

Most fingerprint comparisons are still done by human examiners, who examine two impressions to determine the amount of perceived detail in agreement. Examiners must rely on their training and experience to determine whether the quality and quantity of detail in agreement is sufficient to warrant an identification decision, which makes their perceptual and decision-making abilities central to our understanding of the strength of fingerprint evidence. Research on latent print examiners has documented the influence of configural processing, greater working memory, and greater consistency of eye gaze among experts relative to novices. All of these lead to universally higher accuracy relative to novices. However, examiners must contend with fatigue and the problem of non-mated prints that are somewhat similar in appearance. Surprisingly, this problem only gets worse as databases increase in size. Currently, the field contends with a relatively high number of erroneous exclusions and inconclusive decisions, which may allow a potentially guilty suspect to remain free from charges. We discuss policy implications that follow directly from the research and suggest future research directions that address unresolved issues.

Psychonomic Bulletin & Review, 2010

Latent print examiners face a daunting task. Fingerprints are often the only physical evidence left at a crime scene, but these are typically invisible until developed and lifted. Even after they are dusted with lifting pow-