Forensic Science International: Reports最新文献

Short tandem repeat (STR) markers are commonly used in forensic investigations and kinship testing due to their cost-effectiveness and high discriminatory power. In the United Kingdom, STR allele frequency databases are available for different population groups, including the White group, which includes individuals of both English and Irish ethnicity. However, considering differences in historical migrations and influences between England and Ireland, distinct genetic differences might exist between these populations. This study aimed to generate allele frequency data for English and Irish populations using the VeriFiler Express PCR Amplification Kit, which contains loci utilised in national databases. Buccal swabs were collected from 577 English and 500 Irish volunteers with self-proclaimed English and Irish ethnicity respectively. DNA profiling and statistical analyses were performed to assess allele frequencies and forensic parameters, and to perform population comparisons. The results showed minimal genetic differentiation (F_st = 0.0013) between the English and Irish populations. Comparison with other European populations revealed close genetic relationships between the English population and Scandinavian countries, while the Irish population displayed closer genetic links to Western European countries. These findings support historical influences such as Viking migrations and highlight the need for further research using additional markers to explore the genetic makeup and history of the English and Irish populations. Although a single allele frequency database may be suitable due to the observed genetic similarity, the establishment of separate databases should be considered to ensure maximum population representation.

Manual analysis of hand radiographs for sex estimation is prone to biases and errors. This study addresses the need for automated methods by exploring the potential of Convolutional Neural Networks (CNNs) to accurately identify individual sex from Thai hand radiographs, overcoming limitations in data availability and variable quality. To improve dataset quality, we applied contrast limited adaptive histogram equalization (CLAHE) and Gaussian blur filter techniques to Thai hand radiographs from 385 male and 788 female individuals. We split these images into training, validation, and test sets. We also applied image augmentation techniques to increase the number of radiographs in the training dataset. Seven CNN models were trained, validated, and evaluated on 100 unseen male and female radiographs each. Among these models, the InceptionResNetV2 architecture demonstrated superior performance, achieving an accuracy of 87.50 % and an F1-Score of 86.91 %. Notably, this model utilized information from the 2nd to the 5th metacarpal bone and proximal phalanges in males, and from the 2nd metacarpal bone in females. Our findings provide a solid foundation for sex estimation from Thai hand radiographs, highlighting the power of CNNs in mitigating challenges associated with data quantity and quality. By automating the sex estimation process using CNNs, forensic analysis can benefit from enhanced accuracy and objectivity, enabling faster and more reliable sex assessment. We envisage that future research will build upon these findings to further improve the performance of sex estimation, contributing to advancements in forensic analysis and facilitating more effective utilization of Thai hand radiographs for sex estimation.

This study analyzed the differences in the decomposition patterns and post mortem intervals of hanged and surface carcasses using domestic pigs as human analogs. Six domestic pigs weighing between 25 kg and 30 kg were separated into two groups comprising three pigs each. Three pigs were hanged on the branches of trees at the research facility; whereas the other three pigs were placed on the soil surface. Daily periodic decomposition observations were noted and scored for a period of 30 days alongside the accumulated degree days. There is a statistically significant (P = 0.001) difference in the decomposition between hanged and surface pigs. The hanged pigs decomposed faster at the initial stage reaching a total body score (TBS) of 10 by the second day but gradually slowed down and mummified; whereas the surface pigs initially decomposed at a slower rate but later sped up at about 167 ADD till complete skeletonization. ADD and TBS are very reliable and accurate predictors for PMI estimation of surface and hanged pig carcasses. Insect colonization of a carcass is a very important factor that determines the rate of decomposition of hanged and surface pig carcasses in Okuku, Nigeria. There is a statistically significant difference in the decomposition rate and pattern of hanged and surface pig carcasses. The prediction models for estimating PMI considered ADD and TBS as variables, and these prediction models are very reliable at 95 % confidence level.

Research on how to reliably reconstruct the shape of the ear for facial approximations is limited, especially in countries such as South Africa where standard ear casts are still used in manual methods. To improve objectivity, computer aided methods are being developed for facial approximations – which require extensive population specific datasets for facial feature morphology. This study aims to assess variations in the shape of the ear and the underlying external auditory meatus (EAM) through the analysis of cone-beam computed tomography (CBCT) scans of 40 black South Africans (males n = 17; females n = 23) and 76 white South Africans (males n = 29; females n = 47) between the ages of 18 and 90 years. Shape data was collected by placing 19 capulometric landmarks on the 3D reconstructions of the ear and 46 sliding craniometric landmarks along the EAM. Geometric morphometric analysis revealed highly significant variation in ear shape between groups for population affinity (p-value = 0.001), while sex and age were only significant between the white South Africans (p-value < 0.05). Only population affinity significantly influenced shape in the EAM (p-value = 0.001), and both the ear and EAM showed significant levels of symmetry (p-value = 0.007). While an ear will never be exactly recreated, basing facial estimates on the decedent’s biological profile can lead towards the highest possible accuracies. For the ear shape specifically, sex and age will not be a priority when creating predictive models, but population affinity will greatly influence the output.

Background and aim

Tooth development and eruption are widely used in assessing dental age estimation, and one of the methods in using tooth development and eruption is Foti’s method. However, the population used in the original study was French. Therefore, the aim of this study was to test the accuracy of Foti’s four dental age estimation regression models against the East London population, mainly of the Bangladeshi and Caucasian ethnicity. These count the number of erupted teeth and tooth germs using a radiograph (Foti 1), absence of a radiograph (Foti 2), maxillary erupted teeth (Foti 3) and mandibular erupted teeth (Foti 4).

Methods

The test sample was archived panoramic radiographs of 754 healthy patients aged 6–20 years (380 males and 374 females). The difference between dental and chronological ages was tested using a t-test. The mean absolute difference was also calculated for all models. The most accurate method was defined as the smallest mean difference, smallest standard deviation (SD) and mean absolute difference between dental and chronological ages.

Results

Foti model 2 was most accurate with a mean difference of 0.11 years (SD 1.70 years) and a mean absolute difference of 1.33 years. Models 3 (maxillary erupted teeth) and 4 (mandibular erupted teeth) were marginally less accurate, whilst model 1 (radiograph) overestimated age on average by more than 5 years.

Conclusion

Our findings show that estimating age using erupting teeth was most accurate using Foti model 2 (least bias).

Bone and teeth can often be the only, or the best, biological materials available as DNA sources for the identification of decomposed or skeletal human remains. While these hard tissues are resistant to decay and therefore offer endogenous DNA a certain protection from the environment, their mineral matrices make DNA extraction challenging, a problem compounded by the low DNA content and high degradation levels usually associated with these tissues. To help release DNA from the mineral matrix, they are generally ground into a powder to increase their surface area to the extraction reagents. Furthermore, it is now common to perform a demineralization to dissolve the powder and release DNA that remains trapped. A common pulverization method consists of the use of a cryogenic grinder, which prevents heating of the sample and avoids subjecting the DNA to heat damage, but this equipment is costly. That said, little is known about the effect of lower-cost alternatives to the expensive cryogenic grinder on the quality and quantity of DNA recovered. Thus, this study aimed to evaluate inexpensive grinding methods for their potential for use in a forensic laboratory setting. The methods deemed to be viable options for this purpose were investigated to determine their effects on the quantity and quality of extracted DNA. Bone samples were also subjected to freezing prior to pulverization to assess the possibility that a lower sample temperature could limit heat damage to the DNA during processing. Pig bone and tooth powders were extracted using an original and a modified PrepFiler BTA™ Kit protocol, with the latter featuring an added demineralization step. Out of the methods explored, a coffee grinder and mortar and pestle were determined to be the most suitable for bone and teeth processing in a forensic laboratory setting. No significant differences between the two methods were found regarding the quantity and quality of DNA recovered and the rate of powder recovery, although more powder loss occurred when teeth were crushed with the mortar and pestle. Likewise, freezing samples before grinding did not have a significant impact on DNA quality and quantity. Finally, the original DNA extraction protocol performed significantly better than the modified one for the quantity of DNA recovered from both bone and teeth, while the quality was only superior for the bone.

Different methods of suicide, when combined with contamination of the scene, increase the difficulty of interpreting the dynamics of an event. In the presented case, the discovery of a corpse with widespread burns, singed hair, an “X”-shaped cut on the arm with a weapon distant from the body, and the death scene significantly altered by subjects with psychiatric disorders raised the hypothesis of murder in the initial phase. However, the integration of the death scene investigation with medicolegal, toxicological, and radiological analyses allowed for the identification of an unusual unplanned complex suicide by arm cutting, poisoning, and self-immolation.

Objective

This report examines how evidence appears according to the issues of traffic accident investigation, and examines the immediacy of the evidence and its meaning.

Background

In traffic accidents, there may be trace evidence related to the issue. When the investigator does not make a judgment based on evidence, the truth of the case may be distorted by various mistakes that humans can make, such as confirmation bias and eyewitness illusion.

Methods

By investigation process of two traffic accident cases that violated the central line regulation, we examine how evidence was found and its immediacy works.

Results

As evidence, we presented a piece of plastic attached to the underside of the vehicle and several photos showing the distribution of vehicle debris at the time of the accident. Evidence that we found can be easily understood by anyone with common sense and has undeniable clarity in figuring out the facts. The evidence found could immediately overturn the police’s investigation results and be accepted as primary evidence by law enforcement agencies.

Conclusion

Every incident has a judicial problem, and there can be one or more pieces of evidence for resolving it, which can manifest itself in many different ways. When evidence with immediacy is found, the case can be resolved easily and clearly. The field of forensic science can help find such evidence.

Radius is sexually dimorphic bone, a relevant feature in biological profiling necessary in forensic investigations. This study aimed to record the radius morphometry and compare the radius morphometric parameters in terms of sex and laterality. Ninety-six dry-human radii bones were collected, and a total of nine morphometric measurements were recorded viz: Maximum radial length (MRL), Distal Breath (DB), Sagittal Diameter at Mid-shaft (SDM), Transverse Diameter at Mid-shaft, Vertical Head Height (HH), Minimum Head Diameter (MinHD), Maximum Head Diameter (MaxHD), Radial Head (CRH), Circumference at Radial Tuberosity (CRT). Circumference at the mean and maximum values in males was consistently higher than the female values for all parameters measured except the values in SDM and TD, where the minimum values of females + were greater on the right-hand side. For laterality, only DB (p 0.001) for both males and females, SDM for both males (p 0.013) and females (p 0.012), HH for males (p 0.042), and CRT for males (p 0.025) were statistically different. Sex and laterality remained unchanged when age was introduced as a confounding factor. This effectively means that age has no bearing on the sexual dimorphism as well as laterality of this sample. The right side consistently had greater values than the left except for HH and CRT for males without age, as well as CRT for males with age. The study concluded that the radius bone of people of the KwaZulu-Natal region is sexually dimorphic and can be used for sex determination.