Chemical Imaging of Human Fingermark by X-ray Photoelectron Spectroscopy (XPS)

X-ray photoelectron spectroscopy (XPS) is a widely used technique to characterize the surface chemistry of materials. It plays a crucial role in accessing qualitative and quantitative information and in detecting the presence of chemical functional groups on the surface of any material. The forensic methods available to detect and identify elements and organic/inorganic compounds are often destructive, so evidence cannot be re-analyzed. However, XPS allows rapid analysis of samples without damaging them. Recently, an increasing number of forensic researchers have begun to study certain chemical information on fingermarks. In this study, the authors aimed to present the applicability and power of XPS imaging in fingermark analysis which can also provide specific information about the fingermark chemical composition. Herein, monochromated X-ray (Al Kα) spot size was fixed at 50 μm. XPS mapping resulted in the acquisition of spectra at each pixel, in an array of 41 × 30 pixels with a step size of 50 μm. Then, a simple discussion has been made about how the scanned surface spectrum and basic snapshot spectra are used to identify different components at a fingertip of a scanned surface area (~3 mm²). Hence, a fingermark pattern contaminated with caffeine, TiO₂, and Pb/PbO deposited on the silicon wafer can be chemically mapped and visualized by XPS using principal component analysis (PCA). Thus, the present study showed the possible applicability of XPS for the identification of illicit drugs of abuse, gunshot residue, and skin care products on latent fingermark by mimicking a crime scene evidence.     

Distribution of the Minutiae in Hypothenar Palm Prints in Slovak Adults: Indications for Personal Identification

Minutiae are small distinguishing features found along every ridge flow, which make each friction ridge print unique. The most common friction ridge prints found at the crime scene are fingerprints; therefore, the most of the minutiae studies are focused exactly on this kind of prints. The authors believe that further examination and enlargement of the palm print database could result in better use of the palm prints for personal identification. We analyzed a total of 160 palm prints from 40 females and 40 males aged between 18 and 70 years from Slovakia. For the evaluation of the minutiae, the area of the hypothenar had to be marked out. The classification of the minutiae used for this study was based on a modified version of the classification system using the total of 13 types of minutiae. The frequency of every minutiae type was calculated and, using the chi-square test with Yates's correction, bilateral and sex differences were assessed. The relationship between the different types of minutiae was examined with Pearson's correlation test. During the initial phases of the identification process, the focus should be on the least common types of minutiae (Y or M and return), which were found not to correlate; thus, their mutual occurrence is random (e.g., overlap—Y or M, crossbar—return, or Y or M—dock). The results of the present study show which specific minutiae types are the most suitable for personal identification. These findings may be beneficial in more effective outcome of the identification process.     

The Error in “Error Rate”: Why Error Rates Are So Needed,Yet So Elusive

Establishing error rates is crucial for knowing how well one is performing, determining whether improvement is needed, measuring whether interventions are effective, as well as for providing transparency. However, the flurry of activities in establishing error rates for the forensic sciences has largely overlooked some fundamental issues that make error rates a problematic construct and limit the ability to obtain a meaningful error rate. These include knowing the ground truth, establishing appropriate databases, determining what counts as an error, characterizing what is an acceptable error rate, ecological validity, and transparency within the adversarial legal system. Without addressing these practical and theoretical challenges, the very notion of a meaningful error rate is limited.     

Composite Machine Learning Algorithm for Material Sourcing,

This study developed a composite machine learning algorithm for attribution of materials of forensic interest (like ammonium nitrate) to original sources. k-nearest neighbor and random forest models were used for source elimination and classification, respectively, in a two-step, composite algorithm based on particle color, size/shape, and trace element concentration features. Novel approaches for simulation to supplement within-source reference features based on empirically measured multi-lot analyses, an improved hold-one-lot-out method for cross-validation, an assessment of the likelihood of the presence of a reference sample, fusion of the source probabilities from the respective classification models, and the calculation of metrics for assessing ensemble sourcing performance are described. Excellent sourcing predictions were obtained; the sourcing algorithm identified the correct source as the top choice 89% of the time, and the correct source was identified to be an average of 2.7 times more likely than the most likely incorrect source.     

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.     

Prevalence of organic gunshot residues in police vehicles

The present study investigated the organic gunshot residue (OGSR) background level of police vehicles in Switzerland. Specimens from 64 vehicles belonging to two regional police services were collected and analysed by LC-MS in positive mode. The driver’s and back seats were sampled separately to monitor potential differences between locations and to assess the risks of a suspect being contaminated by OGSR during transportation to a police station.The results showed that most of the 64 vehicles were uncontaminated (44 driver’s seats and 38 back seats respectively). Up to six of the seven targeted compounds were detected in a single sample, once on a driver’s seat and twice on back seats. The contamination frequency generally decreased as the number of compounds detected together increased. The amounts detected were in the low ng range and less than amounts generally detected just after discharge on a shooter. Our data indicated that detecting a combination of four or more compounds on a police vehicle seat appears to be a relatively rare occurrence. The background contamination observed was most probably due to secondary transfer from police officers (e.g. through recent participation in a shooting session or firearm manipulation) or from firearms stored in the vehicles. The present results might be used as a recommendation to minimize contact of a suspect with contaminated surfaces if OGSR is implemented in routine work in parallel to IGSR analysis.     

Gaughran vs the UK and public acceptability of forensic biometrics retention

This commentary provides a response to the European Court of Human Rights ruling in the case of Gaughran vs the United Kingdom on 13 February 2020. The Court ruled that the indefinite retention of DNA, fingerprints and facial images from all convicted adults was disproportionate. Using data from a survey on public attitudes, we examine the public acceptability of the police retention of forensic biometrics from the population.     

大鼠挫伤骨骼肌中M1/M2型巨噬细胞时间相关性研究

目的 研究大鼠骨骼肌挫伤后M1/M2型巨噬细胞浸润的动态变化规律结合组织学改变建立损伤时间推断方法.方法 建立大鼠骨骼肌挫伤模型,挫伤后6h、12h、24h、36h、48h、60h、72h、96h、144h、216h、336h为实验组,对照组不进行任何处理.采用HE染色法和免疫荧光多重染色方法观察骨骼肌挫伤后修复规律,...