Distribution of the minutiae in the fingerprints of a sample of the Spanish population

Study of the fingerprints of a Spanish sample for the determination of the hand and finger

The individuality and permanence of fingerprints make of them a very useful feature in the identification of individuals. There are now automated computer programmes that allow a quick comparison between a fingermark and a database. However, in order to assess the strength of evidence in fingerprint identification, complementary information on the frequencies of the different morphological features of the dermopapillary ridges is required. This idea is used in this work as a starting point to evaluate the frequencies of the parameters used in the determination of the hand and finger in a large sample of 2600 fingerprints taken from 134 male and 127 female Spanish population. Based on these fingerprints, the frequencies of different categories of the following parameters were obtained: type of pattern, slope of the apex ridge, subtype of two-delta pattern, ridge tracing, major angle, major ridge count, bisector, rotation of the central ridge, assimilation to loops and slant. Moreover, the results have shown that these characters are useful for the determination of the hand in whorls (two-delta pattern) and loops (one-delta pattern), but not for the determination of the finger. The most useful and classificatory parameter when determining the hand of origin of a two-delta fingerprint is the slope of the apex ridge, and for the one-delta pattern, knowing the location of the delta allows the correct estimation of the hand of a fingerprint in more than 93% of the cases. The data presented in this paper are novel and can be used by latent print examiners to improve the statistical basis of their decisions in reaching conclusions.

Measuring the rarity of core-delta distances in fingerprint patterns in the Dutch population

In latent print examination, a conclusion on an individualization is primarily based on the presence of corresponding minutiae. Depending on the level of correspondence between the minutiae on the fingermark and on the reference print, a match is concluded. However, a fingermark is analyzed on all three levels: general pattern combined with core-delta distance, minutiae, and third-level detail. In the opinion of the authors, next to the conclusion based on minutiae, all information should be included in the final assessment of the evidence if present. In this study, we present the results of frequency data on the combination of fingerprint patterns and their core-delta distances. The frequency data allow examiners to substantiate their subjective opinions on the strength of corresponding patterns and core-delta distances based on measurements. The frequencies of the core-delta distances in this study were obtained by encoding core-delta distances in a collection of more than 20,000 fingerprints containing either a loop or a whorl pattern. The frequencies for the core-delta distances of loop patterns were subsequently compared with data from the National Institute of Standards and Technology. This study will demonstrate that core-delta distances in loop and whorl patterns contribute significantly to the overall evidential strength of fingerprint evidence. By adding pattern and core-delta distance information to the evaluation of fingerprint evidence, more challenging fingermarks could be added to fingerprint case reports.

Statistical feature training improves fingerprint-matching accuracy in novices and professional fingerprint examiners

Forensic science practitioners compare visual evidence samples (e.g. fingerprints) and decide if they originate from the same person or different people (i.e. fingerprint ‘matching’). These tasks are perceptually and cognitively complex—even practising professionals can make errors—and what limited research exists suggests that existing professional training is ineffective. This paper presents three experiments that demonstrate the benefit of perceptual training derived from mathematical theories that suggest statistically rare features have diagnostic utility in visual comparison tasks. Across three studies (N = 551), we demonstrate that a brief module training participants to focus on statistically rare fingerprint features improves fingerprint-matching performance in both novices and experienced fingerprint examiners. These results have applied importance for improving the professional performance of practising fingerprint examiners, and even other domains where this technique may also be helpful (e.g. radiology or banknote security).

Fingerprint analysis for the determination of hand origin (right/left) using the axis slant in whorl patterns

Fingerprints are frequently encountered during both civil and criminal investigations. Fingerprints possess numerous characteristics that assist with personal identification. Determining the hand of origin (right or left) for an individual fingerprint would help reduce investigation time and potentially eliminate certain suspects. In this study, we collected a total of 2 900 single digit fingerprints from 290 individuals, and the whorl axis slant was examined in the 743 whorl pattern fingerprints (385 from the right hand and 358 from the left hand). A slant towards the right side was present in 81.82% of samples from the right hand, while a slant towards the left side was observed in 80.73% of samples from the left hand. After applying a chi-square test to the dataset, the results were found to be statistically significant for the determination of hand origin. Our results suggest that the whorl axis slant in a fingerprint is indicative of hand origin (right or left).

Key points

Single digit fingerprints with whorl pattern were analyzed.

Whorl “axis slant” was used to determine the hand origin.

Right axis slant would indicate the right hand of the print.

Left axis slant would indicate the left hand of the print.

Interpopulational differences in the frequency and distribution of delta types

The classification of the main pattern types, arch, loop and whorls, is based on the number and location of deltas or triradii, which are areas defined by the confluence of three ridge systems carrying different directions on the fingerprint. Despite being areas that give place to an important morphological variability, their study has only been approached from the quantitative point of view, in relation to the number with which they appear per finger, hand, or individual (intensity pattern), and their sexual and population differences; while the qualitative aspects have not been evaluated so far. The following paper aims to study and analyze the qualitative variability, both intra and interpopulation, of the frequency of occurrence of the different types of deltas or triradii, in four fingerprint samples from males of different population origin: 100 individuals from China, 100 individuals from Colombia, 100 individuals from Nigeria and 100 individuals from Romania, which has meant the analysis of 4000 fingerprints. For this purpose, the classification of 24 types used by the Scientific Police and Criminalist Departments of the Guardia Civil of Spain has been employed. The results obtained showed the non-equiprobability of the frequency distribution of the different delta types in the four populations. In all cases, sunk open total deltas (Hat), sunk open total with point (Hat(p)) and tripod long (Tl) were the most frequent types, while the sunk closed total with point (Hct(p)) had the lowest frequency. Furthermore, for the first time, interpopulation differences in the frequency distribution of different types of deltas have become noticeable. The data provided in this paper are a pioneer in the field of dactyloscopy and can be used as a reference by the departments of criminalistics of the different countries for the estimation of the scientific value of the evidence in dactyloscopy.

Identification of sex using discriminant function analysis of fingerprint ridge density at three topological areas among North Indian population

The present study attempted to identify sex of an individual using a fingerprint ridge density at three topological areas in the North Indian population. The study population consisted of 134 males and 136 females aged 17 to 25 years (mean age 19.34±2.12). Ridge density (RD) at radial, ulnar and proximal topological areas of the distal phalanges were determined on the surface area of 25mm2. Fingerprint ridge density in a defined area was significantly higher among females as compared to their male counterparts at radial, ulnar and proximal topological areas for both hands. Sexual dimorphic ratio also supported this trend for all three counting areas in right and left hands. Univariate discriminant function analysis explained that the left 2 radial (L2R) (88.1%) had the highest percentage of accuracy for sex identification, followed by the left 3 ulnar (L3U) (82.1%) and the right 2 ulnar (R2U) (81.6%). Multivariate discriminant function analysis showed that the radial topological area of the left hand was the best predictor of sex with the overall accuracy of 84.4%with following discriminant function equation −8.263 − 0.236(L1R) + + 0.321(L2R) + 0.269(L3R) + 0.268(L4R) − 0.067(L5R).

It can be inferred that ridge density in the radial topological area of left hand is the most reliable tool for identifying the sex of an individual.

Distribution of the minutiae in palmprints: Topological and sexual variability

Palmprints have been systematically less studied than fingerprints, despite being of great use in the identification process. In Spain, they were not included in Automated Fingerprint Identification Systems (AFIS) until 2009. Very few investigations performed within the field of palmprints have assessed the sexual and population variability of the number and distribution of minutiae on its surface, despite the fact that these particularities are the basis for personal identification in forensic science. That is why a study was conducted to assess total, bimanual, and sexual density per morphological regions (superior or distal, thenar, and hypothenar) and per counting areas of 1 cm² on 120 palmprints obtained from 30 male and 30 female individuals of Spanish nationality. Also, the frequency in the location of each type of delta or triradius (a, b, c, d, and t) per count area was calculated. Results have shown a topological variability in the distribution of the density of minutiae, which is similar between sexes and a specular effect between both hands. The most frequent locations of the deltas coincide with areas of high minutiae density. It has also been shown that there are sexual differences in the total number of minutiae, which cannot be due to sexual dimorphism in adult hand size, since minutiae are established at an early stage of fetal development and their number will not change during later postnatal growth. These differences can only be attributed to genetic factors related to sexual determination.

Morphological variability of the earlobe in a Spanish population sample

This article shows the morphological variability of the earlobe in a Spanish population of European origin. The frequencies of four lobe characteristics (attachment, contour, modeling, and size) and their degree of expression were studied. The relationship among the characteristics and the differences involving sex and laterality were also considered. The least frequent morphology, and of main use in solving forensic cases, was the very small size with triangle-pulled contour into the skin and crossed-discontinuous modeling. The most frequent morphology, and most clinically useful, was the medium-sized lobe with free-arched contour and eminent or cross-continuous modeling. The characteristics were all symmetric. Size and modeling showed sexual dimorphism. Some characteristics were associated with each other: attachment with contour and modeling and the contour with modeling and size. The least frequent peculiarities were sharp lobe and virgule. The literature is scarce on this matter, practically non-existent for some characteristics, especially modeling and peculiarities. For the first time, the associations of the ear characteristics were analyzed, and this information could be applied to forensic identification.

Sex, Ancestral, and pattern type variation of fingerprint minutiae: A forensic perspective on anthropological dermatoglyphics

OBJECTIVES

The majority of anthropological studies on dermatoglyphics examine the heritability and inter-population variation of Level 1 detail (e.g., pattern type, total ridge count), while forensic scientists concentrate on individual uniqueness of Level 2 and 3 detail (e.g., minutiae and pores, respectively) used for positive identification. The present study bridges the gap between researcher-practitioner by examining sex, ancestral, and pattern type variation of Level 2 detail (e.g., minutiae).

MATERIALS AND METHODS

Bifurcations, ending ridges, short ridges, dots, and enclosures on the right index finger of 243 individuals (n = 61 African American ♀; n = 61 African American ♂; n = 61 European American ♀; n = 60 European American ♂) were analyzed. The overall effect of sex, ancestry, and pattern type on minutiae variation was assessed using a MANCOVA. ANOVA was used to identify Level 2 detail variables responsible for the variation. Logistic regression was used to classify individuals into groups.

RESULTS

The effect of sex is insignificant. Ancestry is significant (Wilks' λ = 0.053 F value = 2.98, DF = 4,224, P value = 0.02), as is pattern type (Wilks' λ = 0.874 F value = 2.57, DF = 12,592.94, P value = 0.003). The ANOVA reveals that bifurcations are responsible for the variation between ancestral groups, while bifurcations and ending ridges vary between patterns. Logistic regression results suggest that total bifurcations can predict the ancestry of an individual (ChiSq = 6.55, df = 1, Prob > ChiSq = 0.01).

DISCUSSION

Significant minutiae variation between ancestral groups yields information that is valuable in both a forensic and anthropological setting. Am J Phys Anthropol 160:625-632, 2016. © 2015 Wiley Periodicals, Inc.

Fingerprint identification: advances since the 2009 National Research Council report

This paper will discuss the major developments in the area of fingerprint identification that followed the publication of the National Research Council (NRC, of the US National Academies of Sciences) report in 2009 entitled: Strengthening Forensic Science in the United States: A Path Forward. The report portrayed an image of a field of expertise used for decades without the necessary scientific research-based underpinning. The advances since the report and the needs in selected areas of fingerprinting will be detailed. It includes the measurement of the accuracy, reliability, repeatability and reproducibility of the conclusions offered by fingerprint experts. The paper will also pay attention to the development of statistical models allowing assessment of fingerprint comparisons. As a corollary of these developments, the next challenge is to reconcile a traditional practice dominated by deterministic conclusions with the probabilistic logic of any statistical model. There is a call for greater candour and fingerprint experts will need to communicate differently on the strengths and limitations of their findings. Their testimony will have to go beyond the blunt assertion of the uniqueness of fingerprints or the opinion delivered ispe dixit.

Fingerprint ridge density in the Argentinean population and its application to sex inference: A comparative study

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.