Latent Print Examination and Human Factors: Improving the Practice Through a Systems Approach: The Report of the Expert Working Group on Human Factors in Latent Print Analysis

Fingerprints have provided a valuable method of personal identification in forensic science and criminal investigations for more than 100 years. Fingerprints left at crime scenes generally are latent prints—unintentional reproductions of the arrangement of ridges on the skin made by the transfer of materials (such as amino acids, proteins, polypeptides, and salts) to a surface. Palms and the soles of feet also have friction ridge skin that can leave latent prints. The examination of a latent print consists of a series of steps involving a comparison of the latent print to a known (or exemplar) print. Courts have accepted latent print evidence for the past century. However, several high-profile cases in the United States and abroad have highlighted the fact that human errors can occur, and litigation and expressions of concern over the evidentiary reliability of latent print examinations and other forensic identification procedures has increased in the last decade. “Human factors” issues can arise in any experience- and judgment-based analytical process such as latent print examination. Inadequate training, extraneous knowledge about the suspects in the case or other matters, poor judgment, health problems, limitations of vision, complex technology, and stress are but a few factors that can contribute to errors. A lack of standards or quality control, poor management, insufficient resources, and substandard working conditions constitute other potentially contributing factors

Occurrence and associative value of non-identifiable fingermarks

Fingermarks that have insufficient characteristics for identification often have discernible characteristics that could form the basis for lesser degrees of correspondence or probability of occurrence within a population. Currently, those latent prints that experts judge to be insufficient for identification are not used as associative evidence. How often do such prints occur and what is their potential value for association? The answers are important. We could be routinely setting aside a very important source of associative evidence, with high potential impact, in many cases; or such prints might be of very low utility, adding very little, or only very rarely contributing to cases in a meaningful way. The first step is to better understand the occurrence and range of associative value of these fingermarks. The project goal was to explore and test a theory that in large numbers of cases fingermarks of no value for identification purposes occur and are readily available, though not used, and yet have associative value that could provide useful information. Latent fingermarks were collected from nine state and local jurisdictions. Fingermarks included were those (1) collected in the course of investigations using existing jurisdictional procedures, (2) originally assessed by the laboratory as of no value for identification (NVID), (3) re-assessed by expert review as NVID, but with least three clear and reliable minutiae in relationship to one another, and (4) determined to show at least three auto-encoded minutiae. An expected associative value (ESLR) for each mark was measured, without reference to a putative source, based on modeling within-variability and between-variability of AFIS scores. This method incorporated (1) latest generation feature extraction, (2) a (minutiae-only) matcher, (3) a validated distortion model, and (4) NIST SD27 database calibration. Observed associative value distributions were determined for violent crimes, property crimes, and for existing objective measurements of latent print quality. 750 Non Identifiable Fingermarks (NIFMs) showed values of Log10 ESLR ranging from 1.05 to 10.88, with a mean value of 5.56 (s.d. 2.29), corresponding to an ESLR of approximately 380,000. It is clear that there are large numbers of cases where NIFMs occur that have high potential associative value as indicated by the ESLR. These NIFMs are readily available, but not used, yet have associative value that could provide useful information. These findings lead to the follow-on questions, “How useful would NIFM evidence be in actual practice?” and, “What developments or improvements are needed to maximize this contribution?

Applications of Forensic Evidence in Criminal Cases

In 2003, Massachusetts governor Mitt Romney proposed a plan for an infallible death penalty that required irrefutable scientific evidence, effectively removing any doubt regarding potential innocence in death penalty cases. Forensic science encompasses many scientific disciplines including natural sciences and pattern analysis, but not all such areas experience equal amounts of general acceptance or influence in criminal cases. While DNA analysis and fingerprint identification using the Integrated Automated Fingerprint Identification System (IAFIS) are both widely accepted forensic applications, recent events expose concerns regarding the authenticity of other disciplines such as hair and bite mark comparison. Before policymakers address the issue of a reinstated death penalty, they must carefully consider the merits of forensic science as well as the potential dangers. Existing issues and a history of wrongful convictions aided by flawed forensic testimony necessitate further investigation and critical analysis of forensic disciplines and the application of forensic evidence in criminal cases

Quantifying the Reliability of Latent Fingerprint Matching via Signal Detection Theory

The definition of standards in fingerprint identification is currently an issue of discussion in the field. Quantitative standards have been used in the past to provide justifications for conclusions; however, a scientific basis for relying on numerical standards alone currently does not exist. The tradeoff for this combined approach is that conclusions are based on a conclusion that is left to the judgment of the examiner and may not be repeatable. To test the implementation of thresholds for conclusion, this research studied the effects of only considering concrete data in quantitative form. In this case, signal detection theory is applied to latent fingerprint matching by using automated fingerprint identification systems from two different program vendors. By searching a test set of fingerprints multiple times with a wide range of detail entered, values for the number of system-matched minutiae and computed match scores can be studied to determine threshold limits based on the amount of the search returns. This in turn allows for the generation of receiver operating characteristic curves that directly measure the reliability of the system. The results show that the ability of the system to distinguish matches and non-matches properly is partly based on the method by which the searches are evaluated. Furthermore, the searched area of the fingerprint and the size of the database play roles in determining how well the system is able to discriminate between states. Through future comparison against results submitted by latent fingerprint examiners, inferences can be drawn as to the reliability of conclusions based on varying levels of available detail

How Jurors Evaluate Fingerprint Evidence: The Relative Importance of Match Language, Method Information, and Error Acknowledgment

Fingerprint examiners use a variety of terms and phrases to describe a finding of a match between a defendant\u27s fingerprints and fingerprint impressions collected from a crime scene. Despite the importance and ubiquity of fingerprint evidence in criminal cases, no prior studies examine how jurors evaluate such evidence. We present two studies examining the impact of different match phrases, method descriptions, and statements about possible examiner error on the weight given to fingerprint identification evidence by laypersons. In both studies, the particular phrase chosen to describe the finding of a match-whether simple and imprecise or detailed and claiming near certainty-had little effect on participants\u27 judgments about the guilt of a suspect. In contrast, the examiner admitting the possibility of error reduced the weight given to the fingerprint evidence-regardless of whether the admission was made during direct or cross-examination. In addition, the examiner providing information about the method used to make fingerprint comparisons reduced the impact of admitting the possibility of error. We found few individual differences in reactions to the fingerprint evidence across a wide range of participant variables, and we found widespread agreement regarding the uniqueness of fingerprints and the reliability of fingerprint identifications. Our results suggest that information about the reliability of fingerprint identifications will have a greater impact on lay interpretations of fingerprint evidence than the specific qualitative or quantitative terms chosen to describe a fingerprint match

How Jurors Evaluate Fingerprint Evidence: The Relative Importance of Match Language, Method Information, and Error Acknowledgment

Fingerprint examiners use a variety of terms and phrases to describe a finding of a match between a defendant\u27s fingerprints and fingerprint impressions collected from a crime scene. Despite the importance and ubiquity of fingerprint evidence in criminal cases, no prior studies examine how jurors evaluate such evidence. We present two studies examining the impact of different match phrases, method descriptions, and statements about possible examiner error on the weight given to fingerprint identification evidence by laypersons. In both studies, the particular phrase chosen to describe the finding of a match-whether simple and imprecise or detailed and claiming near certainty-had little effect on participants\u27 judgments about the guilt of a suspect. In contrast, the examiner admitting the possibility of error reduced the weight given to the fingerprint evidence-regardless of whether the admission was made during direct or cross-examination. In addition, the examiner providing information about the method used to make fingerprint comparisons reduced the impact of admitting the possibility of error. We found few individual differences in reactions to the fingerprint evidence across a wide range of participant variables, and we found widespread agreement regarding the uniqueness of fingerprints and the reliability of fingerprint identifications. Our results suggest that information about the reliability of fingerprint identifications will have a greater impact on lay interpretations of fingerprint evidence than the specific qualitative or quantitative terms chosen to describe a fingerprint match

IMPROVING THE RIGOR OF THE LATENT PRINT EXAMINATION PROCESS

This PhD thesis is a synthesis of a portfolio of interrelated previously published work that was conducted to improve the rigor, standardization, transparency, and quantifiability of the latent print examination process. The core of the work relates to the development, adoption, and implications of the Extended Feature Set (EFS). EFS is a formal international standard (incorporated in ANSI/NIST-ITL) that defines a method of characterizing the information content of friction ridge impressions — allowing latent print examiners to unambiguously document the bases of their determinations during examination. EFS is the enabling technology that has made all of the other elements of this portfolio of work possible: evaluations of the accuracy and reliability of latent print examiners’ determinations, evaluations of the reliability of examiners’ feature markup, evaluations of examiners’ assessments of sufficiency, evaluations of latent print quality, development of quality and distortion metrics, evaluations of AFIS accuracy, and the development of training materials to assist in improving the uniformity of examiners’ annotations of the features and attributes of friction ridge impressions. The thesis summarizes these previous publications, as well as discussing their implications and possible future research and tools that could leverage this body of work. -- Cette recherche doctorale présente la synthèse d’un portfolio de travaux et de publications ayant pour objectif d’améliorer la rigueur, la standardisation, la transparence et la quantification dans le cadre du processus d’identification des traces papillaires. L’élément fondateur de cette recherche est le développement, l’adoption et les implications du Extended Feature Set (EFS). EFS est un standard formel international (incorporé dans ANSI/NIST-ITL) qui définit la méthode de description des caractéristiques présentes sur les impressions papillaires. Il permet aux experts en lophoscopie de documenter de manière non-ambiguë les observations qui sont à la base des conclusions formulées à la suite des examens. EFS a été le facilitateur qui a rendu possible tous les autres éléments de ce portfolio de recherches, à savoir : l’évaluation de la fiabilité et l’exactitude des conclusions des experts en matière de traces papillaires, l’évaluation de la fidélité des annotations des experts, le développement de mesures de qualité et de la distorsion des traces, l’évaluation de l’exactitude des systèmes AFIS et finalement le développement d’une formation visant à améliorer la reproductibilité, entre experts, des annotations des caractéristiques papillaires et de leurs attributs. Cette recherche doctorale présente une synthèse de l’ensemble de ces travaux publiés et discute des implications de ceux-ci, des voies de recherche future ainsi que les outils qui pourraient y être associés