Changes in Fingerprints and the Quantity of Material Forming the Print Depending on Hand Cleanliness,Gender, and Ambient Conditions

Impressions of friction ridges left on a surface are important evidence for identifying an individual and can be used to confirm his or her presence at the scene of an incident. Factors influencing the durability of fingerprints include the physiological characteristics and cleanliness of the individual, environmental factors, and time. The aim of the study was to determine the effect of atmospheric factors, gender, hand cleanliness and time on the width of friction ridge impressions and the amount of material forming the print. The research shows that factors such as gender, ambient conditions, and hand cleanliness affect the width of the ridge impressions and the quantity of material forming the print. The passage of time significantly reduces both the width of the ridge impressions and the quantity of the material forming the print.     

Integration of Pore Features into the Evaluation of Fingerprint Evidence*

Fingerprint practitioners rely on level 3 features to make decisions in relation to the source of an unknown friction ridge skin impression. This research proposes to assess the strength of evidence associated with pores when shown in (dis)agreement between a mark and a reference print. Based upon an algorithm designed to automatically detect pores, a metric is defined in order to compare different impressions. From this metric, the weight of the findings is quantified using a likelihood ratio. The results obtained on four configurations and 54 donors show the significant contribution of the pore features and translate into statistical terms what latent fingerprint examiners have developed holistically through experience. The system provides LRs that are indicative of the true state under both the prosecution and the defense propositions. Not only such a system brings transparency regarding the weight to assign to such features, but also forces a discussion in relation to the risks of such a model to mislead.     

Powder method for detecting latent fingerprints: a review

The powder technique for detecting latent fingerprints involves the application of a finely divided formulation to the fingermark impression, generally with a glass-fibre or a camel hair brush. The powder gets mechanically adhered to the sweat residue defining the ridge pattern. The furrows which are devoid of the fingerprint residue, do not adhere the powder onto them. The final outcome is that the powder formulation sticks to the ridges, but is easily blown off the furrows. Since the powder is normally coloured, the ridge pattern becomes visible and the latent print is said to have developed.     

Powder method for detecting latent fingerprints: a review

The powder technique for detecting latent fingerprints involves the application of a finely divided formulation to the fingermark impression, generally with a glass-fibre or a camel hair brush. The powder gets mechanically adhered to the sweat residue defining the ridge pattern. The furrows which are devoid of the fingerprint residue, do not adhere the powder onto them. The final outcome is that the powder formulation sticks to the ridges, but is easily blown off the furrows. Since the powder is normally coloured, the ridge pattern becomes visible and the latent print is said to have developed.     

Ridge Width Correlations between Inked Prints and Powdered Latent Fingerprints

A methodology to estimate the time of latent fingerprint deposition would be of great value to law enforcement and courts. It has been observed that ridge topography changes as latent prints age, including the widths of ridges that could be measured as a function of time. Crime suspects are commonly identified using fingerprint databases that contain reference inked tenprints (flat and rolled impressions). These can be of interest in aging studies as they provide baseline information relating to the original (nonaged) ridges’ widths. In practice, the age of latent fingerprints could be estimated following a comparison process between the evidentiary aged print and the corresponding reference inked print. The present article explores possible correlations between inked and fresh latent fingerprints deposited on different substrates and visualized with TiO₂. The results indicate that the ridge width of flat inked prints is most similar to fresh latent fingerprints_, and these should be used as the comparison standard for future aging studies.     

Distortion in Fingerprints: A Statistical Investigation using Shape Measurement Tools

Friction ridge impression appearance can be affected due to the type of surface touched and pressure exerted during deposition. Understanding the magnitude of alterations, regions affected, and systematic/detectable changes occurring would provide useful information. Geometric morphometric techniques were used to statistically characterize these changes. One hundred and fourteen prints were obtained from a single volunteer and impressed with heavy, normal, and light pressure on computer paper, soft gloss paper, 10‐print card stock, and retabs. Six hundred prints from 10 volunteers were rolled with heavy, normal, and light pressure on soft gloss paper and 10‐print card stock. Results indicate that while different substrates/pressure levels produced small systematic changes in fingerprints, the changes were small in magnitude: roughly the width of one ridge. There were no detectable changes in the degree of random variability of prints associated with either pressure or substrate. In conclusion, the prints transferred reliably regardless of pressure or substrate     

Collection of Wet‐Origin Footwear Impressions on Various Surfaces Using an Electrostatic Dust Print Lifter

Electrostatic dust print lift method is known to be able to recover only dry‐origin footwear impression. However, the wet‐origin footwear impression could also be recovered using this method. As the amount of dust accumulated before deposition of the wet‐origin footwear impression increased, the intensity of the footwear impression lifted with this method became stronger. If the footwear impression is not affected by moisture after it is made, the 28‐h old wet‐origin footwear impression could be recovered using this method. The intensity of the lifted footwear impression did not decrease significantly even when the number of sequential steps increased as long as the shoe sole is wet. However, when the moisture on the shoe sole depleted, the intensity of the footwear impression decreased sharply. This method has the advantage of being able to enhance the footwear impression without being affected by the footwear impressions deposited in the past.     

Barefoot impressions--a preliminary study of identification characteristics and population frequency of their morphological features

Footprint impressions of 107 male adults ranging in age from 19 to 67 years were recorded and examined. Included in this study were foot impressions from a pair of monozygotic twins as well. The impressions were recorded and converted into a set of indices which essentially are width-versus-length ratios of prominent features of the human foot. These indices were then correlated to yield probability values for use in this study and for comparison to data published by previous investigators Qamra, Abbott, Lovejoy, Cassidy, and Robbins. Friction ridge minutae were not considered in this study. Crease marks, well impressions, and toe step measurements were considered, but not incorporated in the probability values, because of the unique aspect of these features and the inability, at present, to convert these features to mathematical indices. These features do, however, introduce a subjective nature to the analysis scheme. This study uses the combined index probabilities of foot impressions so that the data generated can be used to assign a given probability that a particular foot impression, even without clear definable individual features, can be linked to the person who made the impression.     

Estimation of stature from static and dynamic footprints

The ability to estimate accurately from known parameters is a fundamental aspect of science and is evident as an emerging approach in the area of footprints and stature estimation within the field of forensic identification. There are numerous foot dimensions that have been measured in the literature to predict stature with varying degrees of confidence but few studies have tried to link the strength of estimation to anatomical landmarks. Such an approach is utilised in this study which estimates stature from the right footprints of sixty one adult male and female UK participants. Static and dynamic footprints were taken from each volunteer using the 'inkless paper system'. The prints were digitised and twelve length, width and angle measurements were chosen for the analysis. The highest correlations with stature were shown to be the heel to fourth toe print for the static group of footprints (r=0.786, p<0.01), and the heel to fifth toe print in the dynamic footprints (r=0.858, p<0.01). Collinearity statistics suggest the heel to fifth toe print length measurement is independent and not influenced by any other variables in the estimation of stature for the dynamic prints. Linear regression equations for this measurement presented the smallest standard error of estimate (SEE) and highest shared variance (R(2)) of all included variables (SEE 4.16, R(2) 0.74). Our study discusses a potential anatomical explanation as to why the lateral border of the foot and hence the impression it makes upon a hard surface, is a more stable indicator in the estimation of stature. The investigation recommends the use of Calc_A4 and Calc_A5 length measurements when estimating stature from footprint impressions.     

Sexual Dimorphism in Finger Ridge Breadth Measurements: A Tool for Sex Estimation from Fingerprints

Previous research has demonstrated significant sexual dimorphism in friction ridge skin characteristics. This study uses a novel method for measuring sexual dimorphism in finger ridge breadths to evaluate its utility as a sex estimation method from an unknown fingerprint. Beginning and ending in a valley, the width of ten parallel ridges with no obstructions or minutia was measured in a sample of 250 males and females (N = 500). The results demonstrate statistically significant differences in ridge breadth between males and females (p < 0.001), with classification accuracy for each digit varying from 83.2% to 89.3%. Classification accuracy for the pooled finger samples was 83.9% for the right hand and 86.2% for the left hand, which is applicable for cases where the digit number cannot be determined. Weight, stature, and to a lesser degree body mass index also significantly correlate with ridge breadth and account for the degree of overlap between males and females.     

Two-dimensional metric comparisons between dynamic bare footprints and insole foot impressions-forensic implications

Footwear may be found at crime scenes as physical evidence. Such footwear often has impression features of the wearer’s foot on the insole of the shoe. Scientific research and literature have established that footprints are distinct. This study compares two-dimensional measurements on bare footprints to foot impressions on insoles to determine if significant differences or similarities exist. Dynamic footprints were collected from 51 donors using the Identicator® Inkless Shoe Print Model LE 25P system. Seven foot length and width measurements were taken based on the Reel linear measurement method. Footprint measurements between bare footprints and foot impressions on the insoles were compared. Only two differences (p > 0.05) were observed between the various bare footprint and insole foot impression measurements on the right and left side for most of the measurements, CALC (p < 0.001) and A1 (p = 0.04). Bare footprint and insole A5 measurements on the left side were also significantly different (p = 0.015). The results of the study have implications in the forensic analysis of foot impression evidence on insoles in footwear in assisting with identifying the wearer of said footwear. Situations may arise in the forensic context when comparing the foot impression on the insole of footwear to a suspect’s bare footprint or a footprint from post-mortem remains. This study contributes to the scant literature available on the topic and to understanding the similarities and differences observed in the various linear measurements that may be utilized in the comparison process of footprint impressions on shoe insoles to bare footprints.     

Segmental Hair Analysis—Interpretation of the Time of Drug Intake in Two Patients Undergoing Drug Treatment

The present study involved segmental testing of hair in two clinical cases with known dosage histories. Hair analysis confirmed the first patient's exposure to the prescribed sertraline and citalopram for several months. Citalopram was generally distributed along the hair shaft in accordance with the drug ingestion period. By contrast, “false” positive results were observed for sertraline in distal hair segments, corresponding to a period of no sertraline exposure, which may indicate incorporation from sweat or sebum, which transport the drugs along the hair surface. The second patient received various drugs during her treatment for brain cancer. Metoclopramide, morphine, oxazepam, paracetamol, sumatriptan, tramadol, and zopiclone, which had been part of the therapy, were all detected in the proximal hair segment. The results of these two cases indicated that results—especially concerning the time of drug intake—must be interpreted with caution and allow for the possibility of incorporation from sweat or sebum.     

Chemical Differences Are Observed in Children’s Versus Adults’ Latent Fingerprints as a Function of Time*

Abstract: The identification of aged latent fingerprints is often difficult, especially for those of children. To understand this phenomenon, the chemical composition of children’s versus adults’ latent fingerprints was examined over time using Fourier transform infrared microscopy. Hierarchical cluster analysis revealed that children’s and adults’ prints were distinguishable for up to 4 weeks after deposition, based on differences in sebum composition. Specifically, adults had a higher lipid content than children, but both decreased over time, attributable to the volatility of free fatty acids. The aliphatic CH₃, aliphatic CH₂, and carbonyl ester compositions changed differently in adults versus children over time, consistent with higher cholesterol and cholesteryl esters in children’s prints and wax esters and glycerides in adults’ prints. Thus, fingerprint composition changes with time differently in children versus adults, making it a sensitive metric to estimate the age of an individual, especially when the age of the print is known.     

Latent Fingermark Aging Patterns (Part IV): Ridge Width as One Indicator of Degradation

This fourth article of the series is taking an in‐depth analysis at the visible aging of latent fingermarks regarding changes in ridge widths over time. The objective is to quantify and statistically describe significant ridge size variations under controlled indoor conditions. The effect of three environmental variables are examined: type of secretion (sebaceous‐ and eccrine‐rich) and type of substrate (glass and polystyrene) when aged in three light conditions (direct natural light, shade, and dark). Prior to width measurements, fresh and aged fingermarks were powdered with titanium dioxide (TiO₂) and sequentially photographed at predetermined times over 6 months. Three independent observers measured the ridges from thirty predetermined locations using strategically placed intersecting lines on the print. Results indicate that fingermarks deposited on glass are more resilient to degradation compared with those deposited on plastic. The presence of direct natural light plays a negligible role on degradation compared to secretion and substrate types.     

Impact of aging on fingerprint ridge density: Anthropometry and forensic implications in sex inference

The variation in the epidermal ridge's width between the sexes, during various growth stages, and among different populations has been previously assessed. However, the changes that occur with aging are barely known.The goal of this study was to analyse the degree of variation in epidermal ridge width due to aging. So that, fingerprint ridge density was estimated to establish their relationship with body and hand size changes that typically occur in adulthood.In this study, a sample of 213 adults of both sexes from a Spanish native population of different age ranges—18–30?years old (“junior” group) and 50–66?years old (“senior” group)—was used. Ridge density was assessed in three counting areas of the distal phalanx of each finger (radial, ulnar, and proximal). Height, weight, and a set of anthropometric measurements for both hands were also taken.Our results show that ridge density is higher in females than males throughout adulthood and decreases with aging in the radial and ulnar areas (as the hands widen) but not in the proximal region. Thus, a relationship between hand dimensions and ridge density was found.The data indicate that aging changes may conceal the recognized sex differences in ridge density, and so a better understanding of the topological variations in the epidermal ridge width throughout the life cycle and the factors involved would facilitate the interpretation of the differences between the sexes and different age groups.     

Fingerprint Ridge Density as a Potential Forensic Anthropological Tool for Sex Identification

In cases of partial or poor print recovery and lack of database/suspect print, fingerprint evidence is generally neglected. In light of such constraints, this study was designed to examine whether ridge density can aid in narrowing down the investigation for sex identification. The study was conducted on the right‐hand index digit of 245 males and 246 females belonging to the Punjabis of Delhi region. Five ridge density count areas, namely upper radial, radial, ulnar, upper ulnar, and proximal, were selected and designated. Probability of sex origin was calculated, and stepwise discriminant function analysis was performed to determine the discriminating ability of the selected areas. Females were observed with a significantly higher ridge density than males in all the five areas. Discriminant function analysis and logistic regression exhibited 96.8% and 97.4% accuracy, respectively, in sex identification. Hence, fingerprint ridge density is a potential tool for sex identification, even from partial prints.     

A Small Population Study on Friction Skin Ridges: Differences in Ridge Widths Between Latent and Inked Fingerprints

Morphological changes in the width of latent fingermark ridges occur naturally over time. This could be used to examine the aging process of latents and eventually estimate time of deposition. In a crime context, it is common practice to compare a questioned (aged) fingermark with a database of known (inked) prints. Therefore, in the absence of fresh fingermarks for aging purposes, it is of interest to reveal correlations between these two categories of fingerprints with regard to the widths of their ridges. The present study explores correlations of ridge widths between flat and rolled inked prints with latent fingermarks visualized with carbon black (CB) and titanium dioxide (TiO₂)-based powders among a small population of ten donors. Results revealed consistent differences between the ridge widths of latent and inked prints as well as flat and rolled impressions. Latent fingermarks visualized with CB and TiO₂ powders showed ridges with comparable widths.     

A study on the use of photopolymer reflex plate in the forgery of Chinese seals

This study compares the identifying characteristics between the impressions made with original Chinese seals and photopolymer replicate seals, and between the impressions made with two photopolymer replicate seals that originate from one single negative. Various seal materials common to the Chinese community such as cow's horns and ivory are employed. Other than the common factors such as different incident angle upon imprinting or different degree of inking that constitute the natural variation in impressions, the physical changes of the seal materials with temperature will be considered. This study concludes that photopolymer replicate seal impressions can be differentiated from the originals in respect to print density and stroke morphology, but it is very difficult to differentiate between two photopolymer replicate seal impressions with the same origin. This study also proposes a simple method for the examination of forged Chinese seal impressions.     

Secondary impressions of writing detected by ESDA

Experiments have been performed which show conclusively that, under certain conditions, ‘impressions’ of writing can be detected by ESDA (ElectroStatic Detection Apparatus) on paper which has been placed in contact with the reverse of paper bearing writing which has significantly embossed the back. Such indirect ‘secondary’ impressions are caused by some degree of lateral relative motion of the two sheets of paper. Secondary impressions can usually be distinguished from normal primary impressions (caused by the ‘act’ of writing) by several characteristics, in particular, by the indistinct, incomplete and, sometimes, diffuse nature of the secondary impression images.     

Consistency and reproducibility in fingermark deposition

A review of the available literature and previous research has suggested that there are several factors associated with the deposition of friction ridge skin marks that can affect the quality of the resultant marks, including the quantity of force applied, the angle of friction ridge and surface contact and the duration of friction ridge and surface contact. A device referred to as a fingerprint sampler was designed and constructed to facilitate the deposition of fingermarks for research projects. Fingermarks were deposited with and without the fingerprint sampler and examined for evidence of distortion. The quality of the marks was also assessed. The results of this study suggested that the fingerprint sampler deposited fingermarks without distortion caused by some physical factors associated with deposition and that the marks were of a statistically significantly higher quality than marks deposited without its use.