Previous research has established the variability of examiners in reaching suitability determinations for friction ridge comparisons. Attempts to create predictive models to assist in this determination have been made, but have been largely confined to fully automated processes that focus on suitability for AFIS entry. This work develops, optimizes, and validates a hybrid predictive model that utilizes both examiner-observed variables and automated measures of quality and rarity to arrive at suitability classifications along four scales that have been proposed in our previous research: Value, Complexity, AFIS, and Difficulty. We show that a model based only on automatically extracted quality or selectivity measures does not perform as well as when used in conjunction with a limited set of user inputs. The model is then based on a limited set of input from the users while taking advantage of automatic measures with a view to limit the user encoding effort while maintaining accuracy. The developed model is able to make predictions at up to 83.13% accuracy when using full study data and maintains similar levels of accuracy in an external validation study. The model achieved accuracy at a similar level to that of examiners asked to make the same suitability determinations across all scales. The model can easily be introduced into an operational laboratory with very little additional operational burden to provide guidance on suitability, complexity, AFIS, and quality assurance decisions; to assist in designing testing and training exercises of progressive difficulty; to describe the difficulty of a mark in testimony; and to provide a consensus-based opinion in laboratories where a second opinion is desired but the laboratory lacks sufficient personnel to form a consensus panel.

Mind-set is a term used in the friction ridge discipline to describe a confirmation bias in which an examiner makes early decisions about their interpretation of a mark but fails to update or reconsider those decisions in light of additional information. This most often occurs during the analysis of a mark when an examiner makes decisions (such as orientation or anatomical source of a mark) to help expedite a manual search or set parameters for an automated search, but fails to re-evaluate these decisions if the initial screening of available exemplars does not yield a comparable area, potentially leading to a miss or an erroneous exclusion. Mind-set can also occur when an examiner believes a comparison may be an identification early in the comparison process and employs poor comparison habits to convince themselves it is true, often creating or adapting comparison notes after seeing the exemplar, straining logic to justify their decision, and potentially leading to an erroneous identification. A recent black box study on palmar comparison accuracy and reliability noted both behaviors in the annotations and notes provided by some study participants. Examples are provided in this paper to serve as a reminder to examiners to not allow mind-set to lead them into errors. Particularly given the high false negative error rates reported throughout the literature, examiners need to make re-considering their initial analysis before rendering an exclusion decision part of their comparison routine.

The first step of a friction ridge examination involves determining the suitability-or value-of an impression. Often, this is interpreted as whether the impression is suitable for comparison. However, examiners tend to be variable in their suitability determinations, and suitability itself can be a multi-faceted decision, comprising suitability for comparison, suitability for exclusion, suitability for identification, suitability for AFIS entry, complexity, and others. We undertook a white box study to explore the different facets of suitability determinations and to measure the specific categories of information upon which examiners most heavily rely when reaching these decisions. Although minutiae count was the best indicator of a value determination, clarity and distortion were better predictors of complexity determinations. Examiners were found to be highly variable in their determinations, as well as in their annotations of what information they relied upon. Some unanimous decisions were reached for only high-quality impressions; there was never unanimity on \"no value\" determinations. Examiners tended to use high-confidence minutiae markers, even when there was connective ambiguity or low clarity. Several new suitability categorizations were introduced and had good usage from study participants, indicating that they might have some value for inclusion in routine casework.

2019 commemorates the 10 year anniversary of the National Academy of Sciences report, \"Strengthening Forensic Science in the United States: A Path Forward,\" and one valuable way to measure progress in forensic science is through published research. The purpose of this study is to examine where the friction ridge discipline stands with respect to published research. Two time periods were selected (2005-2009 and 2010-2014) and two different methods were used to describe research growth and publication trends in this discipline. A bibliometric review was conducted using an online literature-indexing tool, Web of Science™, as well as an empirical method involving subject matter experts. Both methods showed an increased number of friction ridge articles published in scientific journals over time.

During fingerprint comparisons, a latent print examiner visually compares two impressions to determine whether or not they originated from the same source. They consider the amount of perceived detail in agreement or disagreement and accumulate evidence toward same source and different sources propositions. This evidence is then mapped to one of three conclusions: Identification, Inconclusive, or Exclusion. A limitation of this 3-conclusion scale is it can lose information when translating the conclusion from the internal strength-of-evidence value to one of only three possible conclusions. An alternative scale with two additional values, support for different sources and support for common sources, has been proposed by the Friction Ridge Subcommittee of OSAC. The expanded scale could lead to more investigative leads but could produce complex trade-offs in both correct and erroneous identifications. The aim of the present study was to determine the consequences of a shift to expanded conclusion scales in latent print comparisons. Latent print examiners each completed 60 comparisons using one of the two scales, and the resulting data were modeled using signal detection theory to measure whether the expanded scale changed the threshold for an \"Identification\" conclusion. When using the expanded scale, examiners became more risk-averse when making \"Identification\" decisions and tended to transition both the weaker Identification and stronger Inconclusive responses to the \"Support for Common Source\" statement. The results demonstrate the utility of an expanded conclusion scale and also provide guidance for the adoption of these or similar scales.

This study addresses the permanence and persistence of friction ridges and the persistence of impressions made from these friction ridges over months and years. Permanence is the unchanging presence and appearance of friction ridge arrangements and their attributes between recurring observations of the skin. Permanence was evaluated from direct photographs of fingers collected over a period of 30-45 days (covering one or more skin regeneration cycles) as well as after 8 or more years had elapsed. Persistence embodies the operational concept of whether or not a pair of images displays sufficient similarity upon which to base an informed decision that they were made by the same finger, while acknowledging certain dissimilarities or distortions due to friction ridge physiology, image capture, matrix, substrate, and applied pressure. Persistence applies to both friction ridge skin and impressions made from these friction ridges. Permanence and persistence of skin were assessed from direct photographs of fingers taken two months apart and from finger photographs separated by an interval of at least 8 years. Permanence and persistence were also assessed from impressions taken over 4 months, as well as those separated by 8-53 years. Variability due to capture method was assessed by using four image capture methods over a four month period: direct photography of fingers, impressions captured by ink, holographic imaging, and live scan. Qualified latent fingerprint examiners assessed all changes observed over time, as well as any limitations imposed by capture method. The practice of comparison and identification of fingerprint impressions was upheld, as was the prevailing use of the word persistence to describe stability of friction ridges. All photographs and impressions of the same finger were identifiable as originating from the same source. Within all the periods of observation, level 1 detail was permanent and persistent. Persistence, but not permanence, was supported for level 2 detail. Notably, the small changes observed were only in appearance; there were no changes in the presence of new, or absence of existing, minutiae. Level 3 details of ridge edge shape and pore presence were neither permanent nor persistent. Ridge width was permanent and persistent. Incipient ridges were neither permanent nor persistent.

Brass ammunition is commonly found at firearms related crime scenes. For this reason, many studies have focused on evidence that can be obtained from brass ammunition such as DNA, gunshot residue and fingerprints. Latent fingerprints on ammunition can provide good forensic evidence, however; fingerprint development on ammunition casings has proven to be difficult. A method using cold patination fluid is described as a potential tool to enhance friction ridge detail on brass ammunition casings. Current latent fingerprint development methods for brass ammunition have either failed to provide the necessary quality of friction ridge detail or can be very time consuming and require expensive equipment. In this study, the enhancement of fingerprints on live ammunition has been achieved with a good level of detail whilst the development on spent casings has to an extent also been possible. Development with cold patination fluid has proven to be a quick, simple and cost-effective method for fingerprint development on brass ammunition that can be easily implemented for routine police work.