Journal of forensic sciences最新文献

The NGM Detect™ PCR Amplification Kit was designed particularly for genotyping degraded casework samples. This study aimed to validate the half-volume amplification of the kit and to present its successful long-term application. The validation was performed in accordance to the corresponding guidelines of the Scientific Working Group on DNA analysis methods and the European Network of Forensic Science Institutes. For validation parameters, such as sensitivity, reproducibility, and repeatability, polymerase chain reactions (PCR) were set up both manually and robotically, applying 29 cycles. For PCRs with sub-optimal DNA input (≤0.5 ng) the cycle numbers were increased to 31. Regardless of the PCR preparation method, the optimal 0.5 ng DNA input produced optimal allelic peak heights with no allelic dropout. The first alleles that failed to amplify started to appear at the level of 0.0375 ng input DNA, although the manually prepared PCRs produced fewer missing alleles. In this case, the raised cycle number produced 1.9% and 4.4% of dropout for manually and for robotically set up PCRs, respectively. In the case of 84 degraded casework samples, PCRs were prepared only by hand. The kit was able to provide informative profiles for 78.57%, 70.37%, and 69.77% for lowly, moderately, and highly degraded samples, respectively. Allelic dropouts were 26.05%, 44.88%, and 51.23% for the same groups. According to our results, we strongly recommend using the NGM Detect™ Kit in half-volume PCR system and encourage the usage of the kit in the particular cases when other kits fail to produce a complete DNA profile.

Forensic archaeology and anthropology have developed significantly over past decades and now provide considerable assistance to the investigation process of disaster victim recovery and identification. In what are often chaotic death and crime scenes, the formal process of utilizing archaeological methods can bring control, order, and ensure systematic search. Procedures assist in defining scene extent, locating victims and evidence, rule out areas for consideration, and provide standardized recording and quality assurance through dedicated use of standardized forms (pro formas). Combined archaeological and anthropological search methods maximize opportunities to recovery the missing through identifying remains, mapping distributions, and providing accounting of victims at the scene. Anthropological assistance in examinations contributes to individual assessment, resolving commingling and fragmentation issues, and utilizing DNA sampling methods and matching data to reassociate and account for the missing. Utilization of archaeology, anthropology, and DNA matching data provides scope to review crime scene recovery and determine requirements and potential for further survey and retrieval. Adopting the most suitable methods for a particular context can maximize recovery, efficiency, and resource use. Case studies demonstrate the utility of archaeological methods in a range of scenarios. They exemplify the success of multidisciplinary analysis in providing evidence of the sequence of events, the timing of events, the impact of taphonomic processes, the location and accounting of victims, and the demonstration of systematic scene search. The considerations provided in this article, utilizing archaeology and anthropology processes, may assist investigators in planning and implementing responses to mass fatalities.

To establish the correlation between thermal conditions imposed on bloodstains and visualizing effect of enhancement techniques, infrared photography and four chemical enhancement reagents were used to visualize bloodstains following thermal exposure. A black tile was selected as the substrate to intensify the visualization challenge, with a Cone Calorimeter serving as the standardized heating source to control thermal conditions. Compared with standard photography, infrared photography is proven to be a valuable complement to chemical reagents, showing significant advantages in visualizing bloodstains after thermal exposure. However, it is worth noting that infrared image fell short of standard image when bloodstains displayed raised, embossed morphology or when bloodstains almost disappeared under specific conditions. The enhancement effectiveness was found to be strongly correlated with thermal conditions imposed on bloodstains, and the morphology evolution of bloodstains during heating affected the chemical enhancement effect additionally, especially when the bulge morphology was formed, and it was observed that reagents were more effective after removing the dense shell of the bulge. Among the four selected chemical enhancement reagents, fluorescein performed exceptionally well, maintaining its effectiveness even for bloodstains heated at 641°C for 10 min. TMB demonstrated its visualizing ability for bloodstains heated at 396°C for 5 min and heated at 310°C for 20 min. BLUESTAR® followed afterwards, while luminol performed worst. The correlation between thermal conditions imposed on bloodstains and the corresponding visualizing effectiveness of enhancement techniques provides important references for detecting bloodstains at fire scenes.

Pathological dissociation is relatively common in the United States and may be associated with violent or criminal behavior. Dissociative Disorders, especially Dissociative Identity Disorder, are considered controversial diagnoses by some in the psychiatric and legal professions. Individuals who offend during dissociative states may not be criminally responsible if they meet the legal standard for insanity, however, insanity pleas based on dissociative symptoms are rare. This review examined Federal appellate case law for potential legal barriers to the insanity defense for dissociative conditions and any restrictions imposed on related expert evidence. Few rulings directly addressed these questions but there do not appear to be any unique barriers for dissociation-related insanity pleas. Some cases provided valuable insights regarding the admission of expert evidence, effective expert testimony, and the role of defense counsel.

To date, synovial fluid has not been the subject of targeted analysis as a possible substrate to search for the presence of diatoms in the forensic context of drowning. However, its unique characteristics of production and isolation from the external environment could make it suitable for this purpose, similar to what has already been demonstrated in the literature for vitreous humor. By considering this, synovial fluid was analyzed in a specific case that came to our attention, where the coexisting signs of polytrauma and drowning were documented during autopsy, demonstrating a period of vitality during immersion. After a thin smear of the supernatant was obtained from the centrifugation of the synovial fluid sample, diatoms were successfully detected, consistent with those found in other organs and the water of the canal. The detection of diatoms in the synovial fluid was an objective finding, but its generalizability is limited because this was a pilot application. However, in cases where death by drowning is suspected and the body has multiple areas breached by trauma, the technique of analyzing diatoms in the synovial fluid could have great potential. Therefore, it is appropriate to further explore this technique in order to obtain more forensic evidence in such a setting.

The presence of gunshot residue (GSR) in a sample can provide valuable information in forensic investigations by associating a suspect with a shooting incident. However, in order to have confidence in the integrity of the results' interpretation, the possibility of contamination by secondary transfer of GSR occurring during the transportation of a person under custody in a police vehicle should be evaluated. In order to investigate police vehicles as a source for secondary transfer of GSR particles, a total of 51 samples were collected from the rear seats of random police vehicles and used to transport arrested individuals. Results indicated that the type of upholstery of the seats plays a main role in determining the potential for secondary GSR contamination. The potential chance of coming into contact with GSR particles in police vehicles is low. GSR contamination from police vehicles is, maybe, not of a major concern but should be taken into consideration mainly when very few characteristic GSR particles are found on an analyzed sample.

Within the complex world of disaster victim identification, or DVI, forensic science practitioners use a variety of investigative techniques to work toward a common goal: identification of the decedents, bringing closure to the affected communities. Identification is a complex undertaking; the event (disaster) also can be extraordinarily complex, as it may be an acute event, or one that spans months or years. Compounding this time issue, remains may be heavily fragmented, dispersed, commingled, or otherwise disrupted by either the perpetrators or the disaster itself. To help solve these complexities, we explore the use of stable isotope analysis (SIA) in DVI events. SIA can be used with a variety of body tissues (hair, nail, bone, and teeth), and each represents different time depths in a decedent's life. Bone collagen and tooth enamel carbonate are useful to reconstruct an individual's diet and source water intakes, respectively, leading to likely population or geographic origin determinations. Additionally, the carbon and nitrogen isotopic signatures of bone collagen have calculated intraperson ranges. These facts allow investigators to determine likely origin of remains using isotopic data and can be used to link skeletal elements (to an individual), or perhaps more importantly, show that remains are not linked. Application of SIA can thus speed remains identification by eliminating individuals from short lists for identification, linking or decoupling remains, and reducing the need for some DNA testing. These strategies and hypothesis tests should commence early in the DVI process to achieve maximum effectiveness.

Multiple gunshot suicides are relatively rare and present significant challenges for investigators and forensic pathologists. In such cases, assessing the possibility of more than one shot being fired can be crucial in distinguishing homicide from suicide. We present a rare case of multiple self-inflicted gunshot wounds to the chest with severe injury to the heart and left lung. Both the sudden, unexpected death of the man, the unknown source of the firearm, and the number and nature of the injuries sustained seemed quite unusual. The investigation revealed that the wounds were self-inflicted at close range, and the interval between successive shots (estimated by witnesses at up to 2 min) suggests that even multiple gunshot wounds perforating the heart and lungs may not necessarily cause immediate incapacitation. Forensic investigations in such cases should be multi-faceted and include full autopsy and ballistics expertise, as well as witness testimony and medical history.

The subject of inter- and intra-laboratory inconsistency was recently raised in a commentary by Itiel Dror. We re-visit an inter-laboratory trial, with which some of the authors of this current discussion were associated, to diagnose the causes of any differences in the likelihood ratios (LRs) assigned using probabilistic genotyping software. Some of the variation was due to different decisions that would be made on a case-by-case basis, some due to laboratory policy and would hence differ between laboratories, and the final and smallest part was the run-to-run difference caused by the Monte Carlo aspect of the software used. However, the net variation in LRs was considerable. We believe that most laboratories will self-diagnose the cause of their difference from the majority answer and in some, but not all instances will take corrective action. An inter-laboratory exercise consisting of raw data files for relatively straightforward mixtures, such as two mixtures of three or four persons, would allow laboratories to calibrate their procedures and findings.