Latent Impressions Research Articles

Preliminary assessment of fingermark development techniques for recovering faint ridge impressions from persons with ectodermal dysplasia

ABSTRACT Latent fingerprint collection and analysis remain a critical forensic technique in a variety of settings globally. However, the quality of deposited fingermarks depends on a plethora of extrinsic and intrinsic factors, one of which includes how skin diseases or conditions can affect development and recovery of latent fingerprint impressions. One such condition is hypohidrotic ectodermal dysplasia (HED), which involves underdevelopment of partial or complete absence of eccrine glands. This study aimed to establish whether recovered fingermark quality was different between HED-positive and unaffected control individuals, and whether quality of developed marks from HED-positive individuals was higher using chemical versus powder methods. Control and HED-positive individuals deposited fingermarks on three different substrates and two development methods were used per substrate . Developed fingermarks were scored qualitatively and compared statistically. Generally, HED-positive individuals produced significantly lower quality marks than the control group, and powder development (either standard or magnetic black) produced significantly poorer quality fingermarks than chemical methods across most substrates for both HED-positive and control group individuals. Taken together, these results support fingerprint examiners using chemical enhancement techniques preferentially where faint fingermarks are encountered. These results contribute important insight for improving best practice and maximizing evidence recovery from faint fingerprint impressions.

A utility of pores as level 3 features in latent fingerprint identification

Latent fingerprint identification is the most prevalent process used by the forensic community from a long time. Smudgy, blurred, and small fingerprint area of the latent impressions results into the deficiency of the level 2 features i.e. minutiae. Most of the commercially available Automated Fingerprint Identification Systems (AFISs) which mainly dependent on minutiae; seems less efficient in latent fingerprint matching. In this paper, the usefulness of pores (level 3 features) besides minutiae in latent fingerprint matching is examined. An algorithm based on Lindeberg’s automatic scale selection method is proposed for pores extraction in latent fingerprints. The fusion of pores and minutiae at score level is used to re-rank the minutiae based latent matcher. The effectiveness of the proposed algorithm and pores utility are evaluated by observing and comparing the latent recognition accuracy obtained for minutiae matching and matching after fusion. Both minutiae and pores are automatically extracted in latent and reference fingerprints. The experimental results show that the fusion significantly improves the latent recognition rate in comparison to the minutiae matching.

Stature And Sex Estimation From Handprint Measurements In Population Of Sharkia Governorate

Background: At the crime scene, handprints are one of the greatest valuable evidences. Sometimes, latent impressions of hands may be the only evidence left in the crime scene. Using several anthropometric parameters on crime scene evidences as handprint for suggesting stature and sex can play an important role in decreasing number of suspects, in our study we aim to assess the feasibility of handprint measurements in estimation of stature and sex in the local population of Sharkia Governorate. Method: The analyzed study sample consists of 127participants (62 males and 65 females) right-handed between age of (18 and 60 years ) from people of Sharkia governorate, stature was measured and handprints were scanned by (CanoScan lide120) .Handprint parameters were processed and taken using Image j program measuring 21 handprint measurements. Results: As regarding the stature, showed that there is a marked difference between males and females, where males are higher in length than females in this study and all the taken measures showed noticed differences between them, Estimation of Stature from handprint measurements by equations from regression (simple linear and best fitting multiple linear models), in regard to sex estimation, all 21 handprint measurements are sexually dimorphic. In the stepwise analysis of the handprint variables, two measurements were selected: handprint breadth and the distal phalangeal length of the thumb. Conclusion: Stature and sex can be estimated from handprint measurements.

Síntese e Caracterização de Material Híbrido Luminescente à Base de Sílica para Revelação de Impressões Digitais Latentes

As impressões digitais são os vestígios mais frágeis encontrados em locais de crime e requerem um aprimoramento da visibilidade. Com isso, a revelação de impressões digitais latentes requer materiais que possibilitem um salto na qualidade, fornecendo alta efiiência e contraste. Desta forma, este trabalho reporta a síntese de um híbrido orgânico-inorgânico com propriedades luminescentes intensas capazes de revelar impressões latentes que assegurem a qualidade necessária para posterior identifiação através dos pontos característicos. Os resultados demonstram que devido à alta emissão fotoluminescente do material sintetizado, foi possível obter a visualização de cristas bem defiidas, levando a identifiação técnica de vários pontos característicos.

Latent Fingerprint Database Using Reflected Ultra Violet Imaging System

Latent fingerprint is considered as the key evidence during crime scene investigations. Various powder and chemical methods are available for visualizing the latent fingerprints as these finger impressions are not directly visible through the naked eye. However, these methods may damage the finger impressions in case if they are not properly lifted and handled carefully. Preserving the evidential value of the located latent fingerprints, hence becomes pivotal for analyzing and identifying the suspected individual. Nowadays, optical touchless technology is being prevalent for developing and visualizing the latent finger impressions. Reflected Ultra Violet Imaging System (RUVIS) is one such optical touchless device. There are number of powder based latent fingerprint databases available. However, database of latent fingerprints using optical touchless technology is not available in the literature. The paper presents the latent fingerprint database developed and captured using the touch-less acquisition device (RUVIS). Extraction of level 3 features from the latent fingerprints plays a significant role in matching these latent impressions with plain impressions. Further in this paper, level 3 features, particularly pores are extracted using Fully Convolution Neural Network (FCN) from the collected latent fingerprints using the RUVIS.

Christophe Champod, Chris Lennard, Pierre Margot, and Milutin Stolilpovic (2016). Fingerprints and other Ridge Skin Impressions

This second edition will likely reach the same degree of success as the first edition received. In this review, the term skin impression will be used to mean either an uncontrolled skin impression (fingermark) or a controlled skin impression (fingerprint) made by friction ridges on human skin such as those on fingers, palms, or feet. This book is written for those professionals involved in: the development (visualization) of impressions; the analysis of the visualized impressions to determine their suitability; the comparison of suitable visualized impressions with other suitable impressions such as those of known persons (suspects); and the decision process used in making conclusions about comparisons and identifications. The treatment on the detection and enhancement of fingerprints along with its two accompanying appendices make up over 40% of the book. Treated here are not only the traditional methods for visualizing latent impressions and methods for enhancing these when needed, but also methods that have recently been developed. The treatment starts with a presentation of the chemicals found on surface of a finger (particularly on the ridges), where they originate, how well these chemical transfer onto different types of surfaces it touches, and thus creating an impression of the finger on a surface (porous, non-porous, or semi-porous), how stable these chemicals are, and, most importantly, what chemical or physical methods can be used to visualize them. Many latent skin impressions that earlier methods could not easily make visible or fluorescent can now be made more perceptible with some of the newly developed visualization techniques. This portion of the book is most useful to a laboratory person involved in the processing of evidence for latent skin impressions.

Estimation of Stature from Anthropometric Dimensions of Hand and Foot in Egyptian Sample

Estimation of stature from incomplete or mutilated and decomposed skeletal remains has obvious importance in personal identification and considered as one of the “Big Four” parameters required to assist in the identification of an individual. Hand and Foot prints are the most valuable clues and may be the only evidence that be available at the crime scene in the form of latent impressions and stature prediction from these prints may support stature estimation of suspects made by eye-witnesses. The aim of the present study is to analyze the anthropometric relationship between hand and foot dimensions with stature in Egyptian population sample. Measurements of stature, hand and foot dimensions were taken from 97 adults (55 males and 42 females) aged from 21 to 45 years following the standard technique. The results revealed that values of all the measurements are statistically significant higher in males than in females and the standard error of estimate (SEE) was lowest using the measurement of foot length (SEE ± 4.26-3.78 cm for males and females respectively) followed by hand length (SEE ± 5.14-3.94 cm for males and females respectively). Stature was significantly and positively correlated with all hand and foot dimensions while the foot length followed by hand length showed the highest correlation with stature which concluded that foot length and hand length are the most accurate measurements for estimating stature with high accuracy in both sexes.

Development of dry-origin latent footwear impression on non-porous and semi-porous surfaces using a 5-methylthioninhydrin and L-alanine complex

5-methylthioninhydrin (5-MTN) is an amino acid sensitive reagent used for the development of latent fingermarks deposited on porous surfaces such as paper and wood. The present study demonstrates that the 5-MTN can be used as a latent footwear impression enhancement reagent, by reacting with trace multivalent metal ions, which are the main components of the latent footwear impression. 5-MTN and L-alanine complex (MTN-ALA) used for the latent footwear impression development was prepared, by mixing 4.5×10 −3 M 5-MTN (in methanol) and 4.5×10 −3 M L-alanine (in methanol) in 1:1 ratio, and keeping undisturbed at room temperature for 24 h. The latent footwear impressions were deposited on white and black non-porous surfaces (glass plate, polyethylene panel, polypropylene panel, acryl panel, polyvinyl chloride (PVC) panel, poly(methyl methacrylate) (PMMA) panel, acrylonitrile-butadiene-styrene (ABS) panel, tile), and a semi-porous surfaces (painted wood). The latent footwear impressions on these surfaces were treated with MTN-ALA complex by spraying. The fluorescence of footwear impressions (occurred due to the reaction between MTN-ALA and metal complexes) was observed under a 505 nm forensic light source and an orange barrier filter. The enhancement of latent footwear impression was achieved from black surfaces without any blurring. However, the fluorescence (enhancement) of footwear impression was not observed on the white PVC, PMMA, and ABS surfaces, because the incident light interfered and reflected on the surface. The sensitivity of MTN-ALA was superior to 2,2’-dipyridil, which is a representative non-fluorescing footwear impression enhancement reagent, and similar to 8-hydroxyquinoline, which is a representative fluorescing footwear impression enhancement reagent.

Decipherment of Latent Handwritten Impressions – A Case Study

The present work is based on a case received in the State Forensic Science Laboratory, Junga, Himachal Pradesh, India. The laboratory was asked to fix the identity of the deceased by examining the latent impressions present on an identity card found at the crime scene, near the corpse. The writing on the identity card was completely washed out due to weathering, leaving behind only some latent impressions made by the writing instrument in place of writing. The laboratory successfully deciphered the identity of deceased by carefully examining these latent impressions even after a time lapse of about a year. A number of techniques were applied but stereomicroscope again emerges out as a versatile tool for surface examination and gave the best results.

Challenging USB fingerprint scanner security protocol: a methodology using casting agents to capture digit and latent ridge detail to enable access

Fingerprint scanners are used as a form of control with access limited to the beholder of the ridge detail. However, to what extent these devices are capable of providing that control has not been fully explored. This study tested the reliability of a fingerprint scanner in accessing enrolled fingerprint data, when faced with the challenge of fake fingerprints. Ridge detail casts were crafted from moulds, with gelatine and silicone being applied as casting agents. The second stage required participants to place fingerprints on a bottle or tile; these latent impressions were subsequently powdered using Magneta Flake. Provil, a forensic casting material was applied directly onto the powder, creating simulated fingerprints from a latent print. Each of the produced fingerprints then went through a scanning process. All materials tested were able to gain access through the participants' enrolled data. This suggests potential unreliability of the fingerprint scanner in storing pertinent data.

Use of Squid as an Alternative to Human Skin for Studying the Development of Hit Marks on Clothes

The development of latent skin impressions on a variety of fabrics (cotton, rayon, polyester, nylon, and acrylic fabrics in five colors; white, black, yellow, blue and red) has been studied. Squid soaked in artificial sweat solution or de-ionized water was used as an alternative to human skin to make skin impressions on the fabric. A piece of squid was subjected to a constant force, to transfer the skin components onto the fabric. The fabrics bearing the skin impressions were treated with various reagents such as ninhydrin, 1,8-diazafluoren-9-one (DFO), 1,2-indanedione/ Zn (1,2-IND/Zn), Amido black and Hungarian red, to know the most effective method for developing the skin impressions on the fabrics. Comparing the sensitivity of the reagents, stronger development was observed from the impressions made with the artificial sweat soaked squid than the de-ionized water soaked squid. These results show that the development quality of the latent hit mark is influenced by the sweat, as well as other skin components. Also, the development efficiency of the reagents varied depending on the chemistry, color and texture of the fabric. Therefore, before the development of skin impressions on the evidence fabrics, it is suggested to perform a preliminary experiment with different methods on a similar fabric to decide the most sensitive method.

Latent Fingerprint Matching: Performance Gain via Feedback from Exemplar Prints

Latent fingerprints serve as an important source of forensic evidence in a court of law. Automatic matching of latent fingerprints to rolled/plain (exemplar) fingerprints with high accuracy is quite vital for such applications. However, latent impressions are typically of poor quality with complex background noise which makes feature extraction and matching of latents a significantly challenging problem. We propose incorporating top-down information or feedback from an exemplar to refine the features extracted from a latent for improving latent matching accuracy. The refined latent features (e.g. ridge orientation and frequency), after feedback, are used to re-match the latent to the top K candidate exemplars returned by the baseline matcher and resort the candidate list. The contributions of this research include: (i) devising systemic ways to use information in exemplars for latent feature refinement, (ii) developing a feedback paradigm which can be wrapped around any latent matcher for improving its matching performance, and (iii) determining when feedback is actually necessary to improve latent matching accuracy. Experimental results show that integrating the proposed feedback paradigm with a state-of-the-art latent matcher improves its identification accuracy by 0.5-3.5 percent for NIST SD27 and WVU latent databases against a background database of 100k exemplars.

USING A TRIANGULAR MATCHING APPROACH FOR LATENT FINGERPRINT AND PALMPRINT IDENTIFICATION

The identification of fingerprints and palmprints is considered a challenging research line in Biometrics. Nowadays, the accuracy of these techniques highly depends on the quality of the involved impressions, specially if the matching is performed in latent cases. In the present work, a new algorithm that reports a high accuracy in both cases is presented. This proposal requires a minimum amount of manually marked information in latent impressions and deals successfully with problems of missing and spurious minutiae. Moreover, we improved a verification algorithm based on a previously introduced feature model. The algorithm uses a strategy for finding adaptable local matches between substructures obtained from images. The experimental results show that our proposal achieves high accuracy for all cases, despite the major differences that exist between a palmprint and a fingerprint. For latent fingerprint identification our approach shows its robustness in retrieving 258 latents from different size scale of the background dataset, achieving a rank-1 identification rate over 57% in all cases. Carrying out a similar experimentation for latent palmprint identification, our approach achieved a rank-1 identification rate over 75%.

Understanding the sufficiency of information for latent fingerprint value determinations

A latent print examiner's assessment of the value, or suitability, of a latent impression is the process of determining whether the impression has sufficient information to make a comparison. A “no value” determination preemptively states that no individualization or exclusion determination could be made using the impression, regardless of quality of the comparison prints. Factors contributing to a value determination include clarity and the types, quantity, and relationships of features. These assessments are made subjectively by individual examiners and may vary among examiners. We modeled the relationships between value determinations and feature annotations made by 21 certified latent print examiners on 1850 latent impressions. Minutia count was strongly associated with value determinations. None of the models resulted in a stronger intraexaminer association with “value for individualization” determinations than minutia count alone. The association between examiner annotation and value determinations is greatly limited by the lack of reproducibility of both annotation and value determinations.

Fingerprint Reagents with Dual Action: Color and Fluorescence

We define "dual fingerprint reagents" as chemical formulations that produce with latent fingerprints in one stage impressions that are both colored and fluorescent. Solutions containing ninhydrin and group IIb metal salts appear to be true dual reagents. Application of these formulations to latent fingerprints on paper is as efficient as the two-step process beginning with ninhydrin and followed by treatment with metal salt. In the color mode, fingerprint detectability with the two ninhydrin-metal salt reagents (one with zinc chloride and the other with cadmium chloride) is comparable with that of ninhydrin itself, in spite of the difference in color. The sensitivity is significantly higher in the fluorescence mode. To view the latent impressions the exhibits are treated with ninhydrin-metal salt reagents and observed under white light illumination and under fluorescence conditions. Cooling to liquid nitrogen temperature enhances the fluorescence considerably. In the shorter wavelength domain, ninhydrin-metal salt reagents exhibit higher sensitivity than the recently reported dual reagent, genipin. The latter is advantageous, however, in the longer wavelength domain, on paper items with strong self-fluorescence, such as brown wrapping paper or paper printed with fluorescent ink. Upon reduction of the ninhydrin concentration 10-fold, ninhydrin-metal salt formulations become purely fluorogenic reagents; no color is noticed but the fluorescence is as intense as with concentrated solutions. Working at lower concentrations is an advantage from ecological and economical viewpoints.

What shoe was that? The use of computerised image database to assist in identification

The use of a computerised (digital image-based) reference system for the capture, storage and retrieval of shoe soles and uppers has the ability to give quick and reliable information to the investigator in relation to the brand and model of shoe responsible for latent impressions located at crime scenes. The success of the system described is due to the diversity and simplicity of the classification codes, coupled with the ability to search part or all of a shoe sole area. This gives the user greater discriminating power and, with the use of icons and ‘click on’ features, makes the system user friendly when classifying and searching for shoes, thus reducing the possibility of interpretation error.

Small Particle Reagent: Developing Latent Prints on Water-Soaked Firearms and Effect on Firearms Analysis

Abstract Small particle reagent (SPR) is a technique for developing latent prints on watersoaked items. Current research in processing wet firearms indicates that SPR may be a valid technique for developing latent prints with negligible effect on firearms analysis. Six different firearms each composed of different materials were immersed in water at time intervals ranging from eight to thirty-five days. At the end of the first and second phases, all firearms were processed for latent prints using SPR. A third phase involved using cyanoacrylate ester fuming followed by black powder as a generally accepted processing technique. Results of the experiment revealed that SPR yielded more suitable latent impressions than cyanocrylate ester fuming followed by black powder.

Latent Fingerprints on Cartridges and Expended Cartridge Casings

The effects of time and detonation on latent fingerprints from cartridges and cartridge castings were explored. Time alone did not appear to seriously degrade latent fingerprint quality over the three-week period of experimental trials. The greatest effect of detonation seemed to stem from hot gaseous blowback on the external surface of the cartridge casings. Nickel-plated casings, because of their greater chemical resistance and more polished surface, were found less satisfactory as a substrate for latent impressions than brass casings. An interesting technique for development and permanent preservation of latent fingerprint impressions on castridge casings was also described.

Use of Nylon Spray as a Lifting Medium for Latent Impressions

One of the latest developments in the latent fingerprint field is a nylon spray material called Arcote1 which was originally developed for the U. S. Army as an identification aid for obtaining fingerprint impressions from bodies, requiring identification. Arcote joins the present well known and successful materials for the lifting of latent impressions-transparent tape and rubber lifters. This newest product, which in the familiar aerosol container to facilitate handling and storage, satisfies the need for a lifting medium that can be successfully used on curved and irregular surfaces, as well as difficult areas where transparent tape or rubber lifters cannot be used.

A Device for Developing Latent Impressions by Fuming

A Device for Developing Latent Impressions by Fuming