Computation of Likelihood Ratios in Fingerprint Identification for Configurations of Any Number of Minuti

University of Lausanne, Lausanne, Vaud, Switzerland
Journal of Forensic Sciences (Impact Factor: 1.16). 12/2006; 52(1):54 - 64. DOI: 10.1111/j.1556-4029.2006.00327.x


Recent court challenges have highlighted the need for statistical research on fingerprint identification. This paper proposes a model for computing likelihood ratios (LRs) to assess the evidential value of comparisons with any number of minutiæ. The model considers minutiae type, direction and relative spatial relationships. It expands on previous work on three minutiae by adopting a spatial modeling using radial triangulation and a probabilistic distortion model for assessing the numerator of the LR. The model has been tested on a sample of 686 ulnar loops and 204 arches. Features vectors used for statistical analysis have been obtained following a preprocessing step based on Gabor filtering and image processing to extract minutiae data. The metric used to assess similarity between two feature vectors is based on an Euclidean distance measure. Tippett plots and rates of misleading evidence have been used as performance indicators of the model. The model has shown encouraging behavior with low rates of misleading evidence and a LR power of the model increasing significantly with the number of minutiæ. The LRs that it provides are highly indicative of identity of source on a significant proportion of cases, even when considering configurations with few minutiæ. In contrast with previous research, the model, in addition to minutia type and direction, incorporates spatial relationships of minutiæ without introducing probabilistic independence assumptions. The model also accounts for finger distortion.

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    • "In this field, and even with the increasing role of forensic genetics, dermatoglyphics still enjoy a pivotal role. However, despite the great interest in the study of fingerprints in the field of forensic science, most studies focus on pattern type (arch, loop, and whorl) and size (ridge count from triradius to core), while some of fingerprints most relevant characteristics, such as the minutiae or the epidermal ridge breadth, have been less studied (Champod, 1996; Champod et al., 2004; Gutiérrez-Redomero et al., 2011b, 2012; Gutiérrez et al., 2007; National Research Council (NAS), 2009; Neumann et al., 2007, 2006). Regarding ridge breadth, surprisingly, few systematic studies have been carried out on the changes that these undergo during pre-and postnatal development (Babler, 1990; David, 1981; Gutiérrez-Redomero et al., 2011a; Hotz et al., 2011; Králík and Novotn´y , 2003; Loesch and Czy ˙ zewska, 1972; Loesch and Godlewska, 1971). "
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    ABSTRACT: Fingerprint ridge density (RD) is known to vary according to sex and population, and such variation can be used for forensic purposes. The aim of this study was to analyze the fingerprint RD of two samples of the Argentinean population in order to assess their topological, digital, bilateral, sexual, and population differences for subsequent application in the inference of sex. Data were collected from the fingerprints of 172 individuals from the Buenos Aires province and 163 from the Chubut province. RD was assessed for three different count areas for all 10 fingers of each individual. In both sexes and both samples, significant differences among areas were obtained, so that radial-RD>ulnar-RD>proximal-RD. Females presented greater RD than males in all areas and on all fingers. Regarding population differences, no significant differences were found between the Buenos Aires and Chubut samples (except for proximal RD in males). However, both samples showed RD significantly different from that of the Jujuy province. The application of Bayes' theorem allowed for the identification of an RD threshold for discrimination of sexes in these Argentinean samples. In conclusion females consistently exhibit narrower epidermal ridges than males, which may evidence a universal pattern of sexual dimorphism in this trait that can be useful in forensics in the identification of individuals.
    Full-text · Article · Oct 2015 · Homo: internationale Zeitschrift fur die vergleichende Forschung am Menschen
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    • "In the field of human biology, dermatoglyphic studies have traditionally been used for characterizing human populations, at both intra-and intergroup levels, as much for healthy populations [1] [2] [3] [4] as for pathological ones [5] [6] [7]. In the scope of forensic science, fingerprints have been used for personal identification for over a century [8] [9] [10] [11] [12] [13] [14] [15] [16] [17]. "
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    ABSTRACT: In recent times, some studies have explored the forensic application of dermatoglyphic traits such as the epidermal ridge breadth or ridge density (RD) toward the inference of sex and population from fingerprints of unknown origin, as it has been demonstrated that there exist significant differences of fingerprints between sexes and between populations. Part of the population differences found between these studies could be of methodological nature, due both to the lack of standardisation in the position of the counting area, as well as to the differences in the method used for obtaining the fingerprint. Therefore, the aim of this study was to check whether there are differences between the RD of fingerprints depending on where the counting area is placed and how the fingerprints are obtained. Fingerprints of each finger were obtained from 102 adult Spanish subjects (50 females and 52 males), using two methods (plain and rolled). The ridge density of each fingerprint was assessed in five different areas of the dactylogram: two closer to the core area (one on the radial and the other on the ulnar side), two closer to the outermost area of each of the sides (radial and ulnar), and another one in the proximal region of the fingertip. Regardless of the method used and of the position of the counting area, thumbs and forefingers show a higher RD than middle, ring, and little fingers in both sexes, and females present a higher RD than males in all areas and fingers. In both males and females, RD values on the core region are higher than those on the outer region, irrespective of the technique of fingerprinting used (rolled or plain). Regardless of the sex and location of the count area (core or outer), the rolled fingerprints exhibit RD greater than that of the plain ones in both radial and proximal areas, whereas the trend is inverted in the ulnar area, where rolled fingerprints demonstrate RD lesser than that of the plain ones. Therefore, in order for the results of different studies to be comparable, it is necessary to standardise the position of the count area and to use the same method of obtaining the fingerprint, especially when involving a forensic application.
    Full-text · Article · Jan 2013 · Science & Justice
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    • "These models have been based on very heterogeneous , and generally very small, samples and very disparate approaches (studying different types of minutiae, different fingerprint patterns, different fingers and different finger areas) see [17] [18]. Recently, Neumann et al. [22] [23] [24] and Egli et al. [25] reported on the use of likelihood ratios as a means of objectively assessing the evidential weight of corresponding minutiae between a fingermark and a fingerprint. The growing rigor with which forensic evidence is examined in the legislative area has resulted in the need to reconsider some of the basic principles that support forensic disciplines in their recognition as sciences [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38]. "
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    ABSTRACT: In recent years, both scientific and judicial sources have highlighted the need for more knowledge about minutiae variability, in order to improve their statistical application to fingerprint identification. In line with this trend toward improving our knowledge of this subject, the aim of the present study was to calculate the frequency with which 20 types of minutiae appeared in 2780 fingerprint impressions obtained from 278 individuals from two Argentinian population samples (100 individuals from Ramal and 178 from Puna-Quebrada). The different types of minutiae were located, identified, and quantified visually in two areas on the fingerprint, the inside and outside of a circle, the radius of which cut fifteen ridges perpendicularly, starting from the center cut of the axes defining the sectors. The non-equiprobability found in both population samples for the different minutiae types studied demonstrated that the evidential weight provided by these characteristics is not the same when applied in identification processes, whether used quantitatively (numerical standard) or qualitatively (holistic method). The results obtained for both populations were compared statistically with those published previously for a Spanish population sample, which had been collected using the same methodology. This comparison has enabled us to demonstrate, for the first time, the existence of significant differences between populations in minutiae frequencies, independently from the main pattern type.
    Full-text · Article · Jul 2012 · Forensic science international
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