The effect of products containing high concentration corrosive substances on the recovery of fingermarks from non-porous surfaces.

Fingermark recovery plays a crucial role in investigating corrosive substance attacks, which are becoming increasingly common. Building upon previous research, this study aimed to identify effective visualization processes for recovering fingermarks from diverse substrates exposed to wide range of commercially available corrosive materials. The study investigated glass, PVC and HDPE substrates with fingermarks deposited 1 day and 2 weeks before exposure to the corrosive substance, and used commercially available substances at concentrations higher than any previous study. It was found that fingermarks could still be recovered from all substrates studied after exposure to most of the corrosive substances, although in general exposure to corrosive substances was detrimental to the quality of marks recovered. The most detrimental corrosive substances were found to be those based on concentrated sulfuric acid. Black and white powder suspensions were the most effective of all processes used in this study, with the highest recovery rates observed from the glass substrate. Age of mark was not found to have a significant effect on recovery rates. Overall the results show that fingermarks may survive exposure to even the most concentrated acids used in this study and provide the initial basis for guidance on processes that could be used on materials used in corrosive substance attacks.

Behavioral biometric optical tactile sensor for instantaneous decoupling of dynamic touch signals in real time.

Decoupling dynamic touch signals in the optical tactile sensors is highly desired for behavioral tactile applications yet challenging because typical optical sensors mostly measure only static normal force and use imprecise multi-image averaging for dynamic force sensing. Here, we report a highly sensitive upconversion nanocrystals-based behavioral biometric optical tactile sensor that instantaneously and quantitatively decomposes dynamic touch signals into individual components of vertical normal and lateral shear force from a single image in real-time. By mimicking the sensory architecture of human skin, the unique luminescence signal obtained is axisymmetric for static normal forces and non-axisymmetric for dynamic shear forces. Our sensor demonstrates high spatio-temporal screening of small objects and recognizes fingerprints for authentication with high spatial-temporal resolution. Using a dynamic force discrimination machine learning framework, we realized a Braille-to-Speech translation system and a next-generation dynamic biometric recognition system for handwriting.

Effective use of skin microbiome signatures for fingerprint identification.

BACKGROUND: Recent advances have increased the importance of the human microbiome, including the skin microbiome. Despite the hand microbiome research, the factors affecting the composition of the hand microbiome and their personal characteristics are incompletely known. OBJECTIVES: Despite changing environmental factors and personal variation, we aimed to indicate the interpersonal distinction between skin microbiota using simple and rapid molecular methods. METHODS: Over a non-consecutive 10-day period, samples were taken from 10 adult individuals, and ribotyping analysis of the 16S and 23S genes of S. epidermidis was performed on each skin sample. Additionally, EcoRI and HindIII enzyme reactions and variable number tandem repeat (VNTR) reactions of S. epidermidis obtained from DNA samples were performed. The skin microbiomes of individuals were evaluated along with the microbiome profiles left on the surfaces they touched. RESULTS: In the environmental samples taken, it has been observed that people preserve their core skin microbiota characters and carry them to their environment. It was determined that the highest similarity rate was 77.14%, and the lowest similarity rate was 31.74%. CONCLUSION: Our study showed that the core skin microbiota retains its characteristics and leaves traces in environments. The fact that the personal microbiome remains unchanged despite environmental differences and has characteristic features has shown that it can be used in forensic sciences to distinguish individuals from each other. These results with simple and rapid methods further increased the importance and significance of the study. The findings indicate that personal skin microbiota can provide a significant contribution to criminal investigations by increasing accuracy and reliability, especially in forensic analyses.

A stain with all the fixing's - Enhancement of fingermarks in blood using a combined fixative and aqueous protein stain.

The use of protein stains to enhance fingermark ridge detail in blood is a common technique used by forensic practitioners around the world. Amido Black is one of the most favoured protein stains due to its strong staining ability. The most common formulation of Amido Black is methanol based, with an ability to simultaneously fix and stain the blood impression, however methanol is toxic and can disrupt some surfaces, potentially compromising fingermark detail. If the surface is suspected of being a material that is impacted by methanol, there is an alternative aqueous formulation, which requires a fixative step to set the blood prior to staining so as not to wash away potential ridge detail. The multi-step process of aqueous protein stains is tedious and numerous studies have been conducted to improve the formula to achieve a combined fixing/staining solution that performs like the methanolic reagent. A combined fixative and stain formulation of aqueous based Amido Black was compared to a multi-step formulation with a separate sulfosalicylic acid fixative. Of the 243 split fingermark impressions analysed the majority (63.5 %) showed no preference to either treatment, with a marginally greater proportion of the remaining marks slightly favouring the combined fixative and stain formulation. Given that the new combined formulation performed broadly similarly to the existing multi step formulation, the potential time savings of this simpler approach may be beneficial to implement into operational use.

Mass killing during terror attack at the Israel-Gaza border and the role of the Ministry of Health in identification of human remains and their release.

More than 1200 civilians and military were killed in cities and villages by the Hamas attack on October 7th, 2023. The bodies and body-parts had to be identified and released for burial. This report outlines the challenges and mode of operation of the massive disaster victim identification (DVI) efforts. Bodies were delivered to a central mortuary. Each body was coded and undressed for external inspection and documentation of physical elements. Digital fingerprints were recorded and blood or toenails sampled for DNA. Odontology exams were performed by dentists describing dentition, aided by computerized tomography (CT). Whole-body CT was performed in cases the bodies were disfigured or burned from the second week. Simultaneously, families of missing civilians provided physical elements to the police to extract the DNA for antemortem documentation. The police took the responsibility over the reconciliation, which was based on comparison of the ante-mortem and post-mortem fingerprints, aided by DNA profile matching, odontology examination, clinical and/or radiological findings performed by forensic practitioners. Secondary identification elements were used assure the families regarding the identification. Precise scientific identification a was a priority, even if it slowed the rate of bodies release. Families were allowed to view their relative either at the mortuary or before burial. The DVI process required cooperation between several governmental agencies and police. To maximize the effectiveness, a synchronized approach should be adopted, specifying communication channels between the partners and dividing the responsibilities. The DVI should be led by a single, experienced authority to ensure interdisciplinary teamwork. This catastrophe required personal resilience of the teams for rapid and efficient functioning and communication between the partners.

DNA and fingerprint analyses of debris from improvised explosive device.

Improvised explosive devices (IEDs) can be assembled directly from daily items and are easily purchasable and distributable internationally, owing to the absence of government export permits. Hence, their origins are not readily revealed, and they can pose significant adverse effects despite their low manufacturing costs. In this study, the feasibility of identifying fingerprints and deoxyribo nucleic acid (DNA) profiles in various IEDs and samples is investigated. Additionally, the relative positions of debris are identified to set the scope of on-site inspection at terrorist scenes. All samples are categorized into porous and non-porous materials, and LMG test, extraction, quantification, and short tandem repeat (STR) analysis are conducted to view the DNA profile. For fingerprinting, 1,2-IND and CA are utilized for development, followed by quality-control analysis. Although sample acquisition is impossible in some experiments, DNA profiling and fingerprint analysis are possible for all, thus allowing mapping to be performed. This study shows that even when terrorist bombing occurs, if evidence with minimal damage is detected at the scene, then STR profiles and fingerprints can be obtained at a level suitable for AFIS usage. Furthermore, accumulating mapping results from numerous experiments significantly aids in determining the scope of evidence acquisition.

Optimisation and validation of cost-effective water-based solutions of acid fuchsin for detecting fingermarks in blood.

Fingermark impressions in blood are commonly encountered at violent crime scenes and represent a critical trace that can link an individual to the scene. A range of techniques are available for detecting and enhancing bloody impressions; however, many chemical methods involve using hazardous solvents or require alternative light sources to visualise fluorescence. This is particularly challenging for bloody impressions on dark substrates. An alternative treatment is the protein dye known as acid fuchsin (commonly known as 'Hungarian Red'), which can be visualised under both white light and fluorescence lighting. However, there is limited research available on this method, especially concerning its use in detecting bloody fingermarks on dark surfaces and its fluorescence qualities. To address these knowledge gaps, this study broadly aimed to evaluate the effectiveness of acid fuchsin for enhancing bloody fingermarks on a range of common substrates, along with comparing the performance of a formulation made from base components against a commercially-available Hungarian Red reagent. Through a multi-phased experimental approach, results supported an all-in-one treatment that contained 2 % SSA, 0.2 % acid fuchsin, and deionised water as the most effective. This formulation performed as well or better than commercial Hungarian Red, amido black and acid yellow in the validation trial. Enhanced impressions could be visualised under white light on light and dark surfaces, whilst 530 nm excitation provided improved detection via both fluorescence and absorption modes depending on substrate background interference. Moreover, the reagent was applied by spraying directly onto substrates placed at near-vertical angles, with no evidence of any fingermarks being affected by running or inadequate fixing. The ability to enhance and visualise bloody impressions on light and dark surfaces, under white light or excitation, using a single, water-based treatment is highly advantageous to operational crime scene examiners and forensic scientists.

Solving the twin paradox-forensic strategies to identify the identical twins.

Identical twins are also called monozygotic twins which originate from the same zygote that possesses the same genetic make-up. To discriminate between identical monozygotic twins, short tandem repeats has not been found effective, therefore, various techniques, including next-generation sequencing (NGS), are applied. Monozygotic twins can be identified through germ line genomes, through speech using deep learning networks, and through epigenetic analysis. Fingerprint analysis has also been used to distinguish between identical twins, as human beings have unique fingerprints. Two distinct levels of fingerprint are used to distinguish between monozygotic twins based upon the differences in the minutiae points. Examination of the methylation pattern of the genome has an enormous potential to differentiate between identical twins, as the methylation of DNA occurs uniquely to each individual. This article offers an insight into the latest methods and techniques used for the differentiation between the identical twins.

Applications of MALDI mass spectrometry in forensic science.

Forensic chemistry literature has grown exponentially, with many analytical techniques being used to provide valuable information to help solve criminal cases. Among them, matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS), particularly MALDI MS imaging (MALDI MSI), has shown much potential in forensic applications. Due to its high specificity, MALDI MSI can analyze a wide variety of compounds in complex samples without extensive sample preparation, providing chemical profiles and spatial distributions of given analyte(s). This review introduces MALDI MS(I) to forensic scientists with a focus on its basic principles and the applications of MALDI MS(I) to the analysis of fingerprints, drugs of abuse, and their metabolites in hair, medicine samples, animal tissues, and inks in documents.

An unconstrained palmprint region of interest extraction method based on lightweight networks.

Accurately extracting the Region of Interest (ROI) of a palm print was crucial for subsequent palm print recognition. However, under unconstrained environmental conditions, the user's palm posture and angle, as well as the background and lighting of the environment, were not controlled, making the extraction of the ROI of palm print a major challenge. In existing research methods, traditional ROI extraction methods relied on image segmentation and were difficult to apply to multiple datasets simultaneously under the aforementioned interference. However, deep learning-based methods typically did not consider the computational cost of the model and were difficult to apply to embedded devices. This article proposed a palm print ROI extraction method based on lightweight networks. Firstly, the YOLOv5-lite network was used to detect and preliminarily locate the palm, in order to eliminate most of the interference from complex backgrounds. Then, an improved UNet was used for keypoints detection. This network model reduced the number of parameters compared to the original UNet model, improved network performance, and accelerated network convergence. The output of this model combined Gaussian heatmap regression and direct regression and proposed a joint loss function based on JS loss and L2 loss for supervision. During the experiment, a mixed database consisting of 5 databases was used to meet the needs of practical applications. The results showed that the proposed method achieved an accuracy of 98.3% on the database, with an average detection time of only 28ms on the GPU, which was superior to other mainstream lightweight networks, and the model size was only 831k. In the open-set test, with a success rate of 93.4%, an average detection time of 5.95ms on the GPU, it was far ahead of the latest palm print ROI extraction algorithm and could be applied in practice.

Preliminary investigations into the use of the ancient pigments Han blue and Han purple as luminescent dusting powders for the detection of latent fingermarks.

Here we present our preliminary studies into the inorganic pigments Han blue (BaCuSi4O10) and Han purple (BaCuSi2O6) as near-infrared luminescent fingerprint dusting powders. These pigments were developed in ancient China around 800 BCE and both show luminescence in the NIR region. There remains, however, ambiguity in the literature concerning their photophysical properties. Samples of Han blue and Han purple artist's pigments were characterized by optical microscopy, infrared, ultraviolet-visible absorbance and luminescence spectroscopy. Their performance as fingerprint dusting powders, without any further treatment, on non-porous surfaces were compared to exfoliated lipophilic coated Egyptian blue and commercial fluorescent powders in a pilot study. These results demonstrate for the first time that both ancient pigments show promise as alternative dusting powders for latent fingermarks.

Quaternary phosphonium AIEgens nanoparticles as innovative agents for developing latent fingerprints.

Quaternary phosphonium salts, a significant category of organophosphorus compounds, have garnered substantial attention from chemists due to their wide range of applications across various research areas. These compounds are utilized in organic synthesis, catalysis, medicinal chemistry, natural materials, and coordination chemistry. Their versatility and effectiveness in these fields make them valuable tools in scientific research. Despite their extensive use in various applications, the potential of quaternary phosphonium compounds as fluorescent agents for revealing latent fingerprints (LFPs) remains largely unexplored, presenting an exciting opportunity for further research and development in forensic science. In this study, we designed molecules that combine the aggregation-induced emission (AIE) chromophore with triphenylphosphine to create a series of novel AIE amphiphiles, namely TPP1, TPP2, and TPP3. Through precise adjustment of the carbon chain length between the phenoxy group and the terminal triphenylphosphine, we were able to finely tune the nanostructures and hydrophobicity of the materials. TPP3 emerged as the optimal candidate, possessing the ideal particle size and hydrophobicity to effectively bind to LFPs, thus enabling efficient fingerprint visualization with enhanced fluorescence upon aggregation. Our findings introduce an innovative approach to fingerprint visualization, offering high selectivity, superior imaging of level 3 structures, and long-term effectiveness (up to 30 days). Additionally, TPP3's outstanding performance in imaging level 3 structures of LFPs is beneficial for analyzing incomplete LFPs and identifying individuals. By significantly improving the detection and analysis of LFPs, this approach ensures more accurate and reliable identification, making it invaluable for forensic investigations and security measures. The adaptability of these compounds to various fingerprint surfaces highlights their potential in diverse practical applications, enhancing their utility in both forensic science and security fields. This versatility allows for precise fingerprint visualization across different scenarios, making them a critical tool for advancing biometric and security technologies.

Biometric-Tuned E-Skin Sensor with Real Fingerprints Provides Insights on Tactile Perception: Rosa Parks Had Better Surface Vibrational Sensation than Richard Nixon.

The dense mechanoreceptors in human fingertips enable texture discrimination. Recent advances in flexible electronics have created tactile sensors that effectively replicate slowly adapting (SA) and rapidly adapting (RA) mechanoreceptors. However, the influence of dermatoglyphic structures on tactile signal transmission, such as the effect of fingerprint ridge filtering on friction-induced vibration frequencies, remains unexplored. A novel multi-layer flexible sensor with an artificially synthesized skin surface capable of replicating arbitrary fingerprints is developed. This sensor simultaneously detects pressure (SA response) and vibration (RA response), enabling texture recognition. Fingerprint ridge patterns from notable historical figures - Rosa Parks, Richard Nixon, Martin Luther King Jr., and Ronald Reagan - are fabricated on the sensor surface. Vibration frequency responses to assorted fabric textures are measured and compared between fingerprint replicas. Results demonstrate that fingerprint topography substantially impacts skin-surface vibrational transmission. Specifically, Parks' fingerprint structure conveyed higher frequencies more clearly than those of Nixon, King, or Reagan. This work suggests individual fingerprint ridge morphological variation influences tactile perception and can confer adaptive advantages for fine texture discrimination. The flexible bioinspired sensor provides new insights into human vibrotactile processing by modeling fingerprint-filtered mechanical signals at the finger-object interface.

Aggregation-induced emission luminogens for latent fingerprint detection.

For over a century, fingerprints have served as a pivotal tool for identification of individuals owing to their enduring characteristics and easily apparent features, particularly in the realm of criminal investigations. Latent fingerprints (LFPs) are "invisible fingerprints" that are most commonly available at crime scenes and require a rapid, selective, sensitive, and convenient method for detection. However, existing fingerprint development techniques harbour limitations, prompting the exploration of novel approaches that prioritize investigator safety and environmental sustainability. Leveraging the unique photophysical properties of aggregation-induced emission luminogens (AIEgens) has emerged as a promising strategy for on-site analysis of LFP visualization. In this highlight, we have presented a comparative analysis of various AIEgens (organic compounds, metal complexes, nanoparticles, and polymers) for the development and detection of LFPs. Through this examination, insights into the efficiency and potential applications of AIE-based fingerprint development techniques are provided. In addition, several strategies have been proposed for circumventing the limitations of existing AIEgens. We hope that this highlight article will encourage more researchers to investigate AIEgens in LFP detection, contributing to forensic science.

Instant in situ highlighting of latent fingerprints by a green fluorescent probe based on aggregation-induced emission.

Fluorescence sensing of latent fingerprints (LFPs) has gained extensive attention due to its high sensitivity, non-destructive testing, low biotoxicity, ease of operation, and the potential for in situ visualization. However, the realization of in situ visualization of LFPs especially with green emission and rapid speed is still a challenge. Herein, we synthesized an amphibious green-emission AIE-gen TPE-NI-AOH (PLQY = 62%) for instant in situ LFP detecting, which integrates the excellent fluorescence properties of naphthalimide (NI) with a hydrophilic head and the AIE character as well as the donating property of tetraphenylethene (TPE). TPE-NI-AOH in ethanol/water binary solvent was used as an environmentally friendly LFP developer and achieved in situ green-fluorescence visualization of LFPs. The fluorescence signal achieves its 60% saturated intensity in 0.37 s and nearly 100% in 2.50 s, which is an instant process for the naked eye. Moreover, level 3 details and super-resolution images of LFPs could be observed clearly. Besides, the TPE-NI-AOH developer could be stored for at least 6 months, suitable for long-term storage. This instant in situ highlighting method does not require post-processing operations, providing a more convenient, rapid, and efficient detection method of LFPs. This work would inspire the further advancement of fluorescent sensors for fingerprint imaging.

Using the refractive index of latent fingerprints for the quantification and characterisation of sample deposition.

Latent fingerprints (LFPs) are predominantly used for personal identification, but in recent years research has shown their potential for drug screening. Despite this there is no standardised collection method to allow accurate drug test interpretation. We sought to help address this by characterising different variables related to sweat deposition in LFPs as the knowledge is limited. A series of experiments were conducted firstly to validate a novel tool called the Ridgeway (Intelligent Fingerprint Ltd. UK) to quantify the amount of sweat deposited from a LFP using the refractive index (RI). A significant positive correlation was observed between the Ridgeway score (Rs) and LFP mass [r = 0.868, p < 0.01]. The Rs was used as means to investigate optimal sampling to characterise sample deposition for drug screening purposes. It was found with a consistent disposition pressure (300 - 400 g) and surface (glass slide) no significant difference was observed between the left and right index finger [left: p = 0.938; right: p = 0.838]. Significantly higher Rs [p<0.01] were obtained when 10 cumulative LFPs were deposited compared to a single LFP, suggesting a larger sweat quantity. We also wanted to investigate optimal eccrine sweat sampling to confirm drug ingestion over drug contamination of the fingerprint. We found that wearing gloves did not significantly improve mean difference in Rs when compared to no gloves [p = 0.239]. To produce eccrine only LFPs, external contamination (e.g. sebaceous sweat) needs to be removed. Soap with lint free tissue was significantly better for this compared to antibacterial hand gel [p<0.01]. Our findings showed that the Ridgeway tool effectively quantified LFPs at the point of deposition using a refractive index and enabled us to establish conditions for consistent LFP sampling.

How often do fingerprint examiners disagree in routine casework?

During routine casework, fingerprint examiners are required to make decisions pertaining to the sufficiency of friction ridge skin impressions. Prior experimental research has established that differences of opinion between examiners are expected, though it is uncertain if these findings are representative of the decisions made during casework. In this study, 5000 job-cards completed by fingerprint experts of the NSW Police Force were scrutinised to track the differences of opinion that occurred between examiners. Experts recorded 19,491 casework decisions, which resulted in 8964 reported identification and inconclusive determinations. Expert decision making was found to be unanimous in 94.8 % of these determinations; 4.6 % involved one expert-to-expert disagreement; and 0.5 % involved two expert-to-expert disagreements. Nil determinations featured more than two expert-to-expert disagreements. Expert-to-expert disagreements occurred in 3.7 % of all identification and inconclusive casework verification decisions. However, verifying experts were more likely to agree with a prior expert's identification decision, than a prior expert's inconclusive decision. The observed expert-to-expert identification disagreement rate was 2.0 %, whereas the observed expert-to-expert inconclusive disagreement rate was 12.5 %. Overall, most casework disagreements arose due to subjective differences concerning the suitability of friction ridge skin information for comparison or sufficiency for identification. Experts were more concordant in their decision-making with other experts than with trainees, and approximately three times more likely to disagree with a prior trainees' identification or inconclusive decision than a prior experts' identification or inconclusive decision. We assume these differences reflect trainees' developing proficiencies in assessing the suitability or sufficiency of friction ridge skin impression information. Differences of opinion in casework are expected, which exposes the subjective nature of fingerprint decision-making. Computer-based quality metric and likelihood ratio tools should be considered for use in casework to guide examiner evaluations and mitigate examiner disagreements.

Healing Function for Abraded Fingerprint Ridges in Tactile Texture Sensors.

Tactile texture sensors are designed to evaluate the sensations felt when a human touches an object. Prior studies have demonstrated the necessity for these sensors to have compliant ridges on their surfaces that mimic human fingerprints. These features enable the simulation of contact phenomena, especially friction and vibration, between human fingertips and objects, enhancing the tactile sensation evaluation. However, the ridges on tactile sensors are susceptible to abrasion damage from repeated use. To date, the healing function of abraded ridges has not been proposed, and its effectiveness needs to be demonstrated. In this study, we investigated whether the signal detection capabilities of a sensor with abraded epidermal ridges could be restored by healing the ridges using polyvinyl chloride plastisol as the sensor material. We developed a prototype tactile sensor with an embedded strain gauge, which was used to repeatedly scan roughness specimens. After more than 1000 measurements, we observed significant deterioration in the sensor's output signal level. The ridges were then reshaped using a mold with a heating function, allowing the sensor to partially regain its original signal levels. This method shows potential for extending the operational lifespan of tactile texture sensors with compliant ridges.

Latent fingerprint imaging using irradiated novel mixed metal oxides (MXOY, M = Ba, Zn, Al, Ce) nanophosphor.

Latent fingerprint developed at the site of crime is considered as crucial physical evidence in forensic investigation. The mixed metal oxides (MXOY, M = Ba, Zn, Al, Ce) nanophosphor was synthesised by irradiating the precursor solution with 60Co gamma radiation followed by solution combustion method. The structural, morphological, optical characteristics and fingerprint imaging were studied using X-ray diffraction (XRD), scanning electron microscopy, UV-visible spectroscopy and powder dusting method, respectively. The XRD results revealed that the average crystallite size is found to be 30 nm with the estimated bandgap of 3.18 eV. The broadband UV exited luminescence of the phosphors was observed at λMax = 330 nm. The PL spectrum shows three emission bands at 432, 444 and 460 nm that corresponds to blue regions, suggesting that the synthesised nanophosphor is a potential luminous material for latent fingerprinting and luminescent devices.

Analysis of palmprints and soleprints of black-tufted marmosets (Callithrix penicillata): are there similarities to humans?

Friction ridges are important and unique biometric features that have been studied in fingerprint science since antiquity and used for human identification. This study aimed to analyze palmprints and soleprints of Callithrix penicillata, including the description of flexion creases, regions, minutiae classification, and delta counting, in order to evaluate the uniqueness of these data and feasibility of using this information as an identification method. Palmprints and footprints were collected using commercial fingerprint ink on A4 size paper. Following image digitalization using the GIMP (2.10.14) image editing program, regions and flexion creases were identified. A total of 600 minutiae were classified in females (288 palms and 312 soles) and 732 in males (360 palms and 372 soles), and all deltas were counted. It was possible to identify three main inconstant flexion creases, in both palmprints and soleprints, with different distribution and orientation when compared to those in humans. Less variety in the types of minutiae and differences in the distribution of deltas were found when compared to human studies. In addition, the hypothesis of non-coincident characteristics in each sample was confirmed.