Associational Patterns of Scavenger Beetles to Decomposition Stages

Beetles associated with carrion play an important role in recycling organic matter in an ecosystem. Four experiments on decomposition, one per season, were conducted in a semirural area in Bahía Blanca, Argentina. Melyridae are reported for the first time of forensic interest. Apart from adults and larvae of Scarabaeidae, thirteen species and two genera of other coleopteran families are new forensic records in Argentina. Diversity, abundance, and species composition of beetles showed differences between stages and seasons. Our results differed from other studies conducted in temperate regions. Four guilds and succession patterns were established in relation to decomposition stages and seasons. Dermestidae (necrophages) predominated in winter during the decomposition process; Staphylinidae (necrophiles) in Fresh and Bloat stages during spring, summer, and autumn; and Histeridae (necrophiles) and Cleridae (omnivores) in the following stages during those seasons. Finally, coleopteran activity, diversity and abundance, and decomposition rate change with biogeoclimatic characteristics, which is of significance in forensics.     

A Noninvasive and Speculative Method of Visualizing Latent Fingerprint Deposits on Thermal Paper

Latent fingerprint deposits on thermal paper have been visualized noninvasively at visible wavelengths when illuminated with a UV‐A light source (peak 365 nm). A higher intensity UV source (250 W/m² at 0.38 m) gave superior fingerprint visibility when compared with a 60 W/m² (at 0.4 m) source. Removing the visible (blue) component of the light source emission did not adversely affect the visibility of the fingerprint. Sample fingerprints from 100 donors, when examined 24 h after deposition, produced identifiable fingerprints from nearly 34% of fingerprint deposits. A mechanism for the observed visibility is proposed based on low emission of visible wavelengths from areas of thermal paper coincident with the fingerprint deposit, when illuminated with UV. This is likely due to a weak color change in the thermal paper dye arising from protonated amino acid components of the sweat. This effect was not observed on nonthermal paper.     

The Application of Flow Cytometry as a Rapid and Sensitive Screening Method to Detect Contamination of Vitreous Humor Samples and Avoid Miscalculation of the Postmortem Interval

Research into maximizing the speed, precision, and reliability of estimating the postmortem interval (PMI) has been a recurring object of investigation and methodologies based on the vitreous humor (VH) have provided good results. However, contamination from causes not readily apparent, such as blood, can occur, and thus lead not only to an erroneous estimation of PMI, but also interfere with the correct identification of other substances in the VH. We have developed a flow cytometry method which quantifies blood contamination and is able to detect erythrocytes in 1:750,000 dilution of contaminated VH which affects the results of hypoxanthine. It is an improvement on the previous more complex mass spectrometry method, being faster, more sensitive, and readily available. As such, it could be proposed for the rapid screening of appropriate samples by detecting and eliminating blood contaminated samples from PMI estimation.     

TrueAllele® Genotype Identification on DNA Mixtures Containing up to Five Unknown Contributors

Computer methods have been developed for mathematically interpreting mixed and low‐template DNA. The genotype modeling approach computationally separates out the contributors to a mixture, with uncertainty represented through probability. Comparison of inferred genotypes calculates a likelihood ratio (LR), which measures identification information. This study statistically examined the genotype modeling performance of Cybergenetics TrueAllele^® computer system. High‐ and low‐template DNA mixtures of known randomized composition containing 2, 3, 4, and 5 contributors were tested. Sensitivity, specificity, and reproducibility were established through LR quantification in each of these eight groups. Covariance analysis found LR behavior to be relatively invariant to DNA amount or contributor number. Analysis of variance found that consistent solutions were produced, once a sufficient number of contributors were considered. This study demonstrates the reliability of TrueAllele interpretation on complex DNA mixtures of representative casework composition. The results can help predict an information outcome for a DNA mixture analysis.     

An Empirical Study on the Relation Between the Critical Angle for Bullet Ricochet and the Properties of Wood

The properties of a bullet, an object, and the incidence angle determine whether the bullet will penetrate, perforate, or ricochet. In this study, the critical angle for ricochet was established for .32 Auto and 9 mm Luger bullets on Abachi, Southern Yellow Pine, Beech, and Ipe wooden boards. Results show that the critical angle differs depending on caliber and wood type. The critical angle is higher for .32 Auto bullets than for 9 mm Luger bullets and increases with increasing wood density and Janka hardness. The established critical angles for ricochet on the lightest and softest wood (Abachi) are 10.4° and 10.3° for .32 Auto and 9 mm Luger, respectively. For the heaviest and hardest wood (Ipe), the angles were 45.0° and 33.4°, respectively. The combined results on the four tested woods show a strong linear relationship between both the density and the hardness and the critical angle for both calibers.     

The Impact of Daubert on the Admissibility of Forensic Anthropology Expert Testimony

Forensic anthropologists anticipated a significant impact from the 1993 Supreme Court Daubert decision, which addressed the standard of admissibility for expert testimony. In response, many forensic articles cited Daubert in the search for objective techniques or a critique of established subjective methods. This study examines challenges to forensic anthropological expert testimony to evaluate whether Daubert has actually affected the admissibility of such testimony. Thirty cases were identified that addressed the admissibility of the testimony, including 14 cases prior to Daubert and 16 after Daubert. Examination of these cases indicates that post‐Daubert cases do not result in more exclusions. Yet, this lack of exclusions may instead be viewed as a manifestation of the field's overall surge toward more objective and quantifiable techniques in a self‐regulating response to Daubert.     

Caustic Ingestion—A Forensic Overview

The ingestion of corrosive substances may produce severe burns to the upper aerodigestive tract and stomach, particularly if the pH is greater than 12 or less than two. There is a biphasic age grouping with adult cases most often involving self‐harm and pediatric cases accidental ingestion. Three cases are reported to demonstrate characteristic features following the ingestion of potassium hydroxide, glacial acetic acid and Lysol^®, respectively. All deaths were due to the effects of caustic burns to the upper aerodigestive tract, esophagus and stomach with perforation and/or hemorrhage. The extent of injuries in these cases depends on the nature, amount, and concentration of the agent and on the exposure time. A point to note at autopsy is that tissue damage may also occur from postmortem exposure. Typical injuries involve perioral, limb, and trunk burns, with extensive aerodigestive liquefactive/coagulative necrosis causing hemorrhage and perforation.     

An Accelerated Analytical Process for the Development of STR Profiles for Casework Samples

Significant efforts are being devoted to the development of methods enabling rapid generation of short tandem repeat (STR) profiles in order to reduce turnaround times for the delivery of human identification results from biological evidence. Some of the proposed solutions are still costly and low throughput. This study describes the optimization of an analytical process enabling the generation of complete STR profiles (single‐source or mixed profiles) for human identification in approximately 5 h. This accelerated process uses currently available reagents and standard laboratory equipment. It includes a 30‐min lysis step, a 27‐min DNA extraction using the Promega Maxwell^®16 System, DNA quantification in <1 h using the Qiagen Investigator^® Quantiplex HYres kit, fast amplification (<26 min) of the loci included in AmpF?STR^® Identifiler^®, and analysis of the profiles on the 3500‐series Genetic Analyzer. This combination of fast individual steps produces high‐quality profiling results and offers a cost‐effective alternative approach to rapid DNA analysis.     

The Homicide–Suicide Phenomenon: Findings of Psychological Autopsies

Homicide–suicide represents a single episode of violence which may decimate an entire family. This study aimed to further describe motives and context of these tragedies. Psychological autopsies were completed for 18 homicide–suicide cases in Dallas, Texas. This included postevent interviews with surviving family members and review of police and coroner records. Two‐thirds of perpetrators had made either verbal or written threats prior to the homicide–suicide. A simplified typology describing victim–perpetrator relationship and motive type is suggested for future studies and clinical ease. Two‐thirds of perpetrators fell into the category of Intimate‐Possessive, most of whom were depressed men who were abusing substances and undergoing separation. Additional categories included Intimate‐Ailing, Filial‐Revenge, Familial‐Psychotic, and Friend‐Psychotic. Further, implications from this psychological autopsy study regarding risk assessment include use of collateral interviews regarding threats and past violence.     

Why Do People Hang Themselves on Trees? An Evaluation of Suicidal Hangings on Trees in Konya,Turkey, between 2001 and 2008

Hanging is the most common method of suicide in the world, and many public places offer a means or opportunity to carry out the activity. Of 4,452 death examinations and autopsies, there were 378 (8.5%) suicides and suicide method was hanging in 185 (48.9%) cases. In 20 of these (10.8%), the suspension point was the branch of a tree. The incident location was the garden of the victim's house in nine cases, the woodlands in seven cases. The suicides were attributed to psychiatric disorders in nine cases, economic problems in six cases, and family problems in five cases. It is concluded that hanging on a tree as a suicide method is often committed by males and the underlying motive may be different in suicidal hangings on trees occurring at daytime and night. For preventional purposes, the reporting of such suicides in public places by the media may be restricted by local authorities.