Journal of forensic sciences最新文献

Recently, an unusual method of home burglary has emerged in several European countries. Nitric acid is used to attack the tumbler lock of the front door. The aim of this study is to gain insights into the technical functioning of this method and to evaluate the advantages and disadvantages of this modus operandi. For this purpose, four pin-tumbler locks were attached to a custom-made holder and 65% nitric acid was successively injected into the key channel using a syringe. The locks were checked manually and using a CT scanner to see whether the lock was overcome and how the acid did affect the pins and springs. In three out of four cases the lock was overcome. The shortest time was 22 min until the pin pairs could be removed and it was possible to turn the core with a screwdriver. Overall, the results show that the modus operandi works with standard locks. According to the authors, the long duration and the high health risk are significant disadvantages in relation to other overcoming methods.

Rodent scavenging of human remains is repeatedly documented in literature. However, most of this documentation is based on single-case examples. While this information is valuable, it does not provide an in-depth understanding of scavenger behavior in a single environment. Mouse scavenging data, in particular, lack larger sample sizes and data representing the full duration of scavenging activity. In documented cases, mice scavenge primarily the hands, the feet, and the head without significant progression into the rest of the body. At the Forensic Investigation Research Station in Whitewater, Colorado, deer mice (Peromyscus maniculatus group) scavenged tissue from 11 human donors. Motion activated game cameras and regular field photography documented scavenging progression and deer mouse behavior. Deer mice generally showed a preference for skin and fat, rarely consuming enough muscle to expose bone. The most scavenged sections of the body were the limbs and deer mice generally ignored the hands, the feet, and the head, unlike previous documentation. In a few cases, deer mice consumed tissue on the limbs in a distinct trail pattern. Most of the scavenging began in spring. This sample greatly expands on the existing documentation of mice overall and contributes much needed data on the progression of scavenging. Scavengers can have a significant impact on a death scene, so detailed documentation of different scavengers in a variety of environments can prove useful in the investigation process.

In forensic handwriting analysis, it is crucial to understand the relative frequencies of findings relevant to the specific author, especially when using statistical methods. These are factored into the likelihoods used to determine the probabilities for the different authorship hypotheses. However, if ad hoc writings are included in the comparison materials, the representation of a comparison writer's habits can be distorted. An overrepresentation of certain creation time points can be avoided by treating ad hoc series of comparison writing samples as internally homogeneous agglomerates, incorporating only a single value per series into the average relative frequency of a given finding for a comparison writer. Additionally, the proposed approach produces finding counts largely independent of the length of the handwriting sample, which has a positive impact on the efficiency and cost-effectiveness of the expert evaluation.

Animal-related crimes have increased with an increase in the number of pets worldwide, underscoring the importance of animal-related biological evidence at crime scenes. Evidence obtained in cases involving dogs and cats often includes a mixture of human and animal DNA. In this study, we developed a method using droplet digital polymerase chain reaction (ddPCR) to simultaneously identify and quantitatively detect human, dog, and cat DNA in mixed samples. HLA-DRA was chosen as a human-specific marker, OR6D7 as a dog-specific marker, and FLAI-K as a cat-specific marker. The species specificity of each target was confirmed using 14 control DNA samples from 11 mammals and 3 birds. Sensitivity tests determined the limit of detection to be 0.0008 ng/μL for human DNA and 0.00061 ng/μL for dog and cat DNA. In the mixture test, each DNA sample was independently and accurately detected in samples containing trace amounts of all three types of DNA. This study demonstrated the effectiveness of applying ddPCR to forensic case samples from dog- and cat-related incidents. We have presented a reliable method for the accurate identification and quantification of human, dog, and cat DNA simultaneously, offering possibilities for advancements in forensic DNA analysis and related fields.

Forensic firearms and tool mark examiners compare bullets and cartridge cases to assess whether they originate from the same source or different sources. To communicate their observations, they rely on predefined conclusion scales ranging from Identification to Elimination. However, these terms have not been calibrated against the actual strength of the evidence except indirectly through error rate studies. The present research reanalyzes the findings of firearms and cartridge case comparisons from error rate studies to generate a quantitative measure of the strength of the evidence for each comparison. We use an ordered probit model to summarize the distribution of responses of examiners and aggregate the data for all comparisons to produce a set of likelihood ratios. The likelihood ratios can be as low as less than 10, which does not seem to justify the current articulation scale that may imply a strength of evidence of 10,000 or greater. This suggests that examiners are using language that overstates the strength of the evidence by several orders of magnitude.

Sex estimation is a critical component of the biological profile, and forensic anthropologists may use a variety of sex estimation methods depending upon the degree of completeness and state of preservation of the skeletal remains being analyzed. The innominate is widely accepted to be the most sexually dimorphic skeletal element. The Diagnose Sexuelle Probabiliste (DSP) method, which uses 10 measurements of the innominate, was introduced in 2005 and updated as DSP2 in 2017. While DSP2 has been reported to have high classification accuracy rates in studies of South American and European populations, the method has not been widely tested in US samples, and few US practitioners incorporate this method into their casework. The goal of this study was to test the reliability and accuracy of DSP2 using a large, modern sample from the US (n = 174). Two observers, blinded from demographic information associated with each specimen, collected the DSP2 metrics. Intra- and interobserver error analyses showed acceptable levels of agreement for all measurements, except for IIMT. Classification accuracies exceeded 95%, with minimal sex bias, for both observers and using various measurement combinations; however, an inclusivity sex bias occurred with more males reaching the 0.95 posterior probability threshold required by DSP2 to provide a sex classification estimate. Based on its high accuracy, forensic anthropologists in the US may consider incorporating DSP2 into their casework, although we recommend excluding IIMT and using SPU with caution. Additional methods will continue to be needed when the posterior probability threshold is not reached.

This study of 21 youthful parricide offenders (YPOs) ages 11-21 examined the relationship between psychopathology, level of psychopathy, and crime scene behaviors, particularly two forms of "body management": (1) "body movement" and (2) "body alteration." Undoing, a form of body alteration reflecting psychological rather than practical needs, for example, to lessen guilt or symbolically reverse the killing, was present in one-third of the sample. The sample shared common characteristics with juvenile parricide offenders overall in that most of them killed one parent, were victims of chronic child abuse, had one or more psychiatric diagnoses (PTSD was most prevalent), used a firearm, and committed the killings at the family home. Unexpectedly, YPOs who were child abuse victims were not more likely to engage in undoing behaviors than non-abused youth, and over half of the youth with undoing behaviors had elevated psychopathy levels. Three-quarters of youth who moved victim bodies following the murders had elevated psychopathy levels. Similarly, all three youth who transported bodies away from the crime scene had elevated psychopathy levels and conduct disorder. None of the youth with psychotic symptoms engaged in undoing behaviors, altered victim bodies, moved bodies either within or away from the home, or had an elevated degree of psychopathy; they also most often killed using bladed weapons, whereas the nonpsychotic youth usually used firearms. Studies examining the influence of mental illness and psychopathy level on parricidal behaviors by youth are scarce, and to our knowledge this is the largest study to date investigating this area.

For decades, detectives and forensic scientists have relied on friction ridge skin comparisons to identify individuals in criminal investigations. This method involves examining (latent) fingermarks, typically captured as two-dimensional (2D) images, and comparing them with known inked impressions or scans. The comparisons focus on general patterns, the location and orientation of minutiae, and additional characteristics like scars or pores. However, this common process overlooks other potentially valuable factors, such as handedness, biological sex, and the time since deposition, which could provide crucial investigative leads, especially in cases with partial or unclear ridge patterns. This study explored the potential of three-dimensional (3D) optical profilometry (OP) to observe changes in fingermarks ridge height and volume over 7 days while considering hand dominance and biological sex. The results indicated that all the assessed 3D metrics were generally consistent in detecting the effects of sex and handedness, mostly noticeable on aged fingermarks. Specifically, females and impressions from their non-dominant hand exhibited higher values. Additionally, the influence of time was evident, with fresh fingermarks showing significantly larger ridges in terms of height and volume. These findings suggest that 3D OP can enhance the probative value of fingermarks by inferring additional characteristics such as sex, handedness, and the age of the impression. These activity-level propositions could provide useful information in cases where only partial or poor-quality fingermarks are recovered, providing new data dimensions that could lead to more comprehensive forensic examinations.

Advancements in forensic DNA typing technology and methods have increased sensitivity and, while beneficial, carry the weight of more challenging profile interpretation. In response, the forensic DNA community has often requested more complex reference materials to address commonly encountered measurement and interpretation issues such as complex DNA mixtures, DNA degradation, and PCR inhibition. The National Institute of Standards and Technology (NIST) released Research Grade Test Material 10235: Forensic DNA Typing Resource Samples to support the forensic DNA community. Components include three single source samples, two degraded samples, and three mixture samples. As part of the Research Grade Test Material (RGTM) process, automated methods for bottling, alternative sample tube types, and the addition of carrier RNA for stabilizing low-quantity samples were investigated. Both internal and external testing demonstrate the stability of the material over time at 4°C through qPCR testing. In the development of a data portal, users have been allowed to anonymously upload results and compare their data with NIST and others. This report describes the preparation and stability of this material.