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•Diamond™ dye (DD) is a non-destructive dye that can visualize touch DNA.•Touch DNA can be visualized after fingermark enhancement have been performed.•Inhibition of DNA profiling after DD staining and enhancement was examined.•DNA profiles were obtained from treated marks except after cyanoacrylate treatment. A novel method for detection and visualization of latent DNA using Diamond™ Nucleic Acid Dye (DD) staining has been developed. Applying DD to an object has the real potential to visualize DNA on a substrate from which a DNA profile can be generated, but it is important to determine whether this staining will adversely affect other forensic investigational techniques and vice versa. The aim of this study was to examine the interactions between staining a fingermark to detect DNA and then generate a DNA profile in combination with several standard latent fingermark enhancement methods. Six common fingerprint enhancements processes were chosen; (1) black powder, (2) black magnetic powder, (3) red magnetic powder, (4) white powder, (5) aluminum powder and (6) cyanoacrylate fuming. For all six methods, mark enhancement was carried out before DD staining and vice versa. DD is effective in detection of DNA in the presence of both aluminum and white finger mark powders and DD does not compromise the subsequent detection of ridge patterns if DD is applied first. Whilst magnetic powders could be used to successfully enhance latent fingermarks even after DD had been applied to them, latent DNA could not be observed in the marks irrespective of whether magnetic powder was applied before or after DD treatment. Magnetic powders did not adversely affect the profiling of DNA present in the marks. The application of DD to fingermarks did not adversely affect the enhancement of fingermarks using cyanoacrylate fuming. Whilst fluorescent particles resembling cells stained with DD were observed in marks either post-treated or pre-treated with cyanoacrylate vapor, DNA amplification and profiling was not successful. While it may be important in particular investigations to collect DNA profiles from latent fingermarks with continuous ridges and clear minutiae, the main utility of the technique described here would be in relation to investigations where enhancement has resulted in only partial or smudged marks. The results presented here indicate that if it is desirable to visualize latent DNA on an object but it is also planned to treat the object with cyanoacrylate vapor or magnetic powders then it is important to apply DD first, record the location of DNA and then apply the mark enhancement technique. For aluminum and white powder mark treatments such precautions are not important.

Wildlife forensics is defined as providing forensic evidence to support legal investigations involving wildlife crime, such as the trafficking and poaching of animals and/ or their goods. While wildlife forensics is an underexplored field of science, the ramifications of poaching can be catastrophic. The consequences of wildlife crime include disease spread, species and habitat loss, human injury, and cultural loss. Efforts to use forensic science to combat poaching are currently limited to DNA-based techniques. However, fingermark analysis for the identification of perpetrators of wildlife crimes has not been explored to the same extent, despite being a cost-effective, simple-to-use forensic method that is easy to deploy in-field. This review covers literature that has explored fingermark examination techniques used on wildlife-related samples, such as pangolin scales, ivory-based substances, bone, and eggs, as well as feathers and skins, among more obscure trafficked items. Useful preliminary work has been conducted in this subject area, demonstrating that commonly used fingermark analysis techniques can be applied to wildlife-based items. However, many of these studies suffer from limitations in terms of experimental design. More work should be done on creating studies with larger sample sizes and novel approaches should be validated under environmental conditions that mimic real crime scenes. Further research into determining the forensic fingermark analysis techniques that perform the most efficiently in the environmental conditions of the countries where they are needed would therefore benefit legal investigations and help to reduce instances of poaching. •The illegal wildlife trade exploits wildlife to an unsustainable and damaging degree.•Forensic scientists are working to combat the multi-billion-dollar industry of illegal trade.•Fingerprint evidence in wildlife crime is valuable, but often overlooked.•Visualisation techniques have been used on wildlife samples, with variable success.•Additional work is needed to validate promising techniques under field conditions.

•Non-Identifiable Fingermarks (NIFMs) occur often in casework, but are seldom used.•NIFM associations are distinct from conventional fingermark evidence.•NIFM associations are material and have strong potential activity value.•NIFM associations can contribute at different levels in the criminal justice process.•NIFMs have high potential utility, frequent occurrence and require minimal effort. Fingermarks that have insufficient characteristics for identification often have discernible characteristics that can form the basis for lesser – yet still useful – degrees of correspondence and probability of occurrence within a population. Currently, those fingermarks that experts judge to be insufficient for identification are not used as associative evidence. However, recent research has shown large numbers of cases where non-identifiable fingermarks (NIFMs) occur that have high potential associative value. The present work focuses on the resulting questions of, “How useful could associations from NIFMs be in actual practice?” and, “What developments or improvements are needed to take advantage of this very promising potential?” As a first step toward answering these questions, the results of recent research findings on occurrence and associative value of NIFMs were presented to a broad audience of criminal justice participants and stakeholders in the United States, including police investigators, prosecutors, judges, defense attorneys, forensic scientists, and members of the academic and research communities. There were a series of extensive, open ended discussions aimed at obtaining individual reactions, including views on the potential contribution in different circumstances and at different stages in the criminal justice process, issues that would affect this contribution, approaches to development, and areas of concern. This produced several important insights. As a class of evidence, NIFM associations were found to be material, clearly distinct from conventional fingermark evidence, and exceptional among less definitive classes of evidence. A wide range of potential contributions were revealed at different levels in the criminal justice process. Some areas of application are suitable for immediate use. Other areas require further development or research in the methodologies, and still others must await developments in forensic science as a whole. There are important implications for researchers, practitioners, evidence collection strategies and evidence retention policies.

The assessment of fingermark (latent fingerprint) quality is an intrinsic part of a forensic investigation. The fingermark quality indicates the value and utility of the trace evidence recovered from the crime scene in the course of a forensic investigation; it determines how the evidence will be processed, and it correlates with the probability of finding a corresponding fingerprint in the reference dataset. The deposition of fingermarks on random surfaces occurs spontaneously in an uncontrolled fashion, which introduces imperfections to the resulting impression of the friction ridge pattern. In this work, we propose a new probabilistic framework for Automated Fingermark Quality Assessment (AFQA). We used modern deep learning techniques, which have the ability to extract patterns even from noisy data, and combined them with a methodology from the field of eXplainable AI (XAI) to make our models more transparent. Our solution first predicts a quality probability distribution, from which we then calculate the final quality value and, if needed, the uncertainty of the model. Additionally, we complemented the predicted quality value with a corresponding quality map. We used GradCAM to determine which regions of the fingermark had the largest effect on the overall quality prediction. We show that the resulting quality maps are highly correlated with the density of minutiae points in the input image. Our deep learning approach achieved high regression performance, while significantly improving the interpretability and transparency of the predictions.

Fingermark patterns are one of the oldest means of biometric identification. During this last decade, the molecules that constitute the fingermark residue have gained interest among the forensic research community to gain additional intelligence regarding its donor profile including its gender, age, lifestyle or even its pathological state. In this work, the molecular composition of fingermarks have been studied to monitor the variability between donors and to explore its capacity to differentiate individuals using supervised multi-class classification models. Over one year, fingermarks from thirteen donors have been analysed by Matrix-Assisted Laser Desorption/Ionisation Mass Spectrometry Imaging (n = 716) and mined by different machine learning approaches. We demonstrate the potential of the fingermark chemical composition to help differentiating individuals with an accuracy between 80% and 96% depending on the period of sample collection for each donor and size of the pool of donors. It would be premature at this stage to transpose the results of this research to real cases, however the conclusions of this study can provide a better understanding of the variations of the chemical composition of the fingermark residue in between individuals over long periods and help clarifying the notion of donorship. •Qualitatively, almost 30% of all detected compounds are consistent over the year in all the fingermarks of thirteen donors.•The chemical composition of the fingermarks quantitatively varies between donors which can help to differentiate individuals.•The fingermark chemical composition can help differentiating individuals with an accuracy between 80% and 96%.

•Differing conclusions explained in terms of image effects and examiner effects.•Variability among examiners due to implicit individual decision thresholds.•Innovative method of comparing performance of human forensic examiners.•3-level conclusion scale does not precisely represent examiners’ conclusions. Forensic latent print examiners usually but do not always reproduce each other’s conclusions. Using data from tests of experts conducting fingerprint comparisons, we show the extent to which differing conclusions can be explained in terms of the images, and in terms of the examiners. Some images are particularly prone to disagreements or erroneous conclusions; the highest and lowest quality images generally result in unanimous conclusions. The variability among examiners can be seen as the effect of implicit individual decision thresholds, which we demonstrate are measurable and differ substantially among examiners; this variation may reflect differences in skill, risk tolerance, or bias. Much of the remaining variability relates to inconsistency of the examiners themselves: borderline conclusions (i.e., close to individual decision thresholds) often were not repeated by the examiners themselves, and tended to be completed more slowly and rated difficult. A few examiners have significantly higher error rates than most: aggregate error rates of many examiners are not necessarily representative of individual examiners. The use of a three-level conclusion scale does not precisely represent the underlying agreements and disagreements among examiners. We propose a new method of quantifying examiner skill that would be appropriate for use in proficiency tests. These findings are operationally relevant to staffing, quality assurance, and disagreements among experts in court.

[Display omitted] •Permanence is the unchanging appearance of friction ridge detail.•Persistence offers sufficient similarity for operationally relevant identifications.•Level 1 details were permanent; level 2 was persistent but not permanent.•Most level 3 details were neither permanent nor persistent.•The presumption of persistence was upheld. 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.

This study was conducted to evaluate the accuracy and reproducibility of decisions made by practicing latent print examiners (LPEs) when comparing latent fingerprints to exemplars that were acquired by searches of the FBI Next Generation Identification system (NGI). This study builds on the 2009 FBI-Noblis latent print examiner black box study (1, 2), incorporating lessons learned from conducting multiple additional forensic examiner studies. Analyses are based on 14,224 responses from 156 LPEs. Each participant was assigned 100 latent-exemplar image pairs (IPs, 80 nonmated and 20 mated) out of a total of 300 IPs. On mated comparisons, 62.6 % of responses were IDs (true positives), 4.2 % were erroneous exclusions (false negatives), 17.5 % were inconclusive, and 15.8 % were no value. On nonmated comparisons, 0.2 % of responses were erroneous IDs (false positives), 69.8 % were exclusions (true negatives), 12.9 % were inconclusive, and 17.2 % were no value. One participant made the majority of the erroneous IDs in the study, which underscores how decision rates can be highly sensitive to the individual participants in a study. No erroneous IDs were reproduced by different LPEs, but 15 % of erroneous exclusions were reproduced. There is a potential concern that NGI’s size and ability to yield much more similar nonmates (as compared to IAFIS used in (1, 2)) poses an increased risk of false IDs; however, we do not find evidence of an increase in the observed false ID rate. These results suggest that risk mitigation strategies for NGI searches may be working for those agencies that have implemented such strategies. •Black box study of fingerprint comparison decisions resulting from large AFIS searches.•More than half of the false positive errors were made by a single participant.•False ID rates are comparable to [Ulery, PNAS, 2011].•Erroneous exclusion rates have decreased since [Ulery, PNAS, 2011].•Results suggest several possible areas for improvement in policies and practice.

The purpose of this work is to critically analyse the aspects connected both with the measurement of error rates and with the design of proficiency tests and collaborative exercises in the fingerprint domain. All from the dual perspective of practitioners and organizers of PT’s/CE’s. A thorough analysis of the types of errors, of the methods to infer them through black-box studies and PT’s/CE’s is carried out, and the limits to the generalization of error rates are described, providing insightful indication on how to design PT’s/CE’s in the fingerprint domain, which are aimed to represent the complexity of casework. •The accuracy of fingerprint examiners can be calculated not only through black-box studies, but also through PT’s/CE’s.•The likelihood of false positive and false negative rate of fingerprint examination can be estimated through PT’s/CE’s.•To calculate accuracy and likelihood of FPR/FNR is paramount to differentiate between “1-to-1\" and “1-to-n\" scenarios.•The test design and its intended scope influence measured accuracy and likelihood of FPR/FNR and must be representative of casework.•Error rates are referred to a specific population of forensic science providers/examiners participating in the test.

Despite the advent of DNA profiling, fingerprints still play an important role in suspect identification. However, if single crime scene marks may be challenging to identify, overlapping fingermarks, understandably, pose an even greater challenge. In the last decade, mass spectrometry-imaging methods have provided a possible solution to the separation of fingermarks from two or more donors, based on the differential chemical composition. However, there are no studies attempting to separate overlapping marks from the same donor. This is important in relation to fingermark deposition at different times, which could be critical, for example, to ascertain legitimate access to the scene. In the work presented here, we investigate whether Matrix-Assisted Laser Desorption Ionisation Mass Spectrometry Imaging can separate the same donor’s fingermarks deposited at different times based on intra-donor fingermark composition variability. Additionally, the hypothesis that the different times of deposition could be also determined was investigated in the view of linking the suspect at the scene at different times; the dating window of MALDI MSI within the selected molecular range was explored. Results show that it is possible to separate overlapping fingermarks from the same donor in most cases, even from natural marks. Fresh marks (0 days) could be separated from those of fourteen days of age, though the latter could not be distinguished from the set aged for seven days. Due to the use of only one donor, these are to be considered preliminary data, though findings are interesting enough to warrant further investigation of the capabilities and limitations of this approach using a larger cohort of donors.