Simplified field preservation of tissues for subsequent DNA analyses

Successful DNA-based identification of mass disaster victims depends on acquiring tissues that are not highly degraded. In this study, multiple protocols for field preservation of tissues for later DNA analysis were tested. Skin and muscle samples were collected from decaying pig carcasses. Tissues were preserved using cold storage, desiccation, or room temperature storage in preservative solutions for up to 6 months. DNA quality was assessed through amplification of successively larger segments of nuclear DNA. Solution-based storage, including a DMSO/NaCl/EDTA mixture, alcohols, and RNAlater preserved DNA of the highest quality, refrigeration was intermediate, and desiccation was least effective. Tissue type and extent of decomposition significantly affected stored DNA quality. Overall, the results indicate that any tissue preservation attempt is far superior to delaying or forgoing preservation efforts, and that simple, inexpensive methods can be highly effective in preserving DNA, thus should be initiated as quickly as possible.     

Sudden death following exercise testing related to abnormalities of the cardiac conduction system and coronary artery pathology

A case of sudden death following exercise testing in a 33-year-old man is reported. The forensic autopsy showed atherosclerotic stenosis of the left coronary artery, as well as some changes in the cardiac conduction system, including anomalies of the atrioventricular node and moderate fibrosis and fatty infiltration of the branching bundle. This case demonstrates that cardiac arrest during vigorous exercise may be multifactorial and that abnormalities of the cardiac conduction system may have played some role in the fatal issue.     

Suicide by injection of a veterinarian barbiturate euthanasia agent: report of a case and toxicological analysis

The history and toxicological findings of a suicidal case involving injection of a veterinarian barbiturate euthanasia agent (Vetanarcol containing pentobarbital are presented. Blood pentobarbital concentrations compatible with drug overdose were determined. Almost identical levels were found in blood, cerebrospinal fluid (CSF) and vitreous humour (VH). The highest concentration was measured in the bile. The present case is compared with similar rare cases in the literature.     

Hypothermia and undressing associated with non-fatal bromazepam intoxication.

A 42-year-old woman with a history of depression was found unconscious, lying near her car in an early autumn morning. The lower part of her body was undressed and there were multiple purple spots and excoriations on the body suggesting at first a sexual assault. On admission to the intensive care unit, she presented a hypothermia with a central temperature of 28.4 degrees C. The biological samples obtained at the hospital were analysed. Blood concentration of bromazepam was 7.7 mg/l, which is above the highest level reported till now in a case of fatal intoxication.     

Evaluation of a simplified method of the conduction system analysis in 110 forensic cases

A simplified method of the His bundle analysis is evaluated by the study of 110 forensic cases. The atrioventricular node or its part were observed in 96 cases (87.3%), penetrating bundle in 92 cases (83.6%), branching and left bundles branch in 109 cases (99.1%) and right bundle branch in 73 cases (66.4%). The changes such as fibrosis and fatty infiltration show statistically significant differences (P<0.01) between progressive age groups confirming their degenerative and age-related nature. The study included as well nine cases of sudden unexpected death and two cases of sudden infant death syndrome (SIDS), for which the autopsy with histological examination and toxicological analysis resulted negative. For nine of these cases, pathological lesions were found which can even explain the fatal issue. Moreover, in the cases with known cause of death, potentially lethal changes were noticed. This simple, low cost technique could be proposed to forensic pathologists as easy to fit into the routine processing of autopsy material, allowing the detection of major abnormalities with minimal effort. The authors also consider the difficulties related to the interpretation of the pathological findings in the conduction system.     

Chemical Enhancement Techniques of Bloodstain Patterns and DNA Recovery After Fire Exposure*

Abstract: It is common in forensic casework to encounter situations where the suspect has set a fire to cover up or destroy possible evidence. While bloodstain pattern interpretation, chemical enhancement of blood, and recovery of deoxyribonucleic acid (DNA) from bloodstains is well documented in the literature, very little information is known about the effects of heat or fire on these types of examinations. In this study, a variety of known types of bloodstain patterns were created in a four‐room structure containing typical household objects and furnishings. The structure was allowed to burn to flashover and then it was extinguished by firefighters using water. Once the structure cooled over night, the interior was examined using a bright light. The bloodstains were evaluated to see if the heat or fire had caused any changes to the patterns that would inhibit interpretation. Bloodstain patterns remained visible and intact inside the structure and on furnishings unless the surface that held the blood was totally burned away. Additionally, a variety of chemical techniques were utilized to better visualize the patterns and determine the possible presence of blood after the fire. The soot from the fire formed a physical barrier that initially interfered with chemical enhancement of blood. However, when the soot was removed using water or alcohol, the chemicals used, fluorescein, luminol, Bluestar^®, and Hemastix^®, performed adequately in most of the tests. Prior to DNA testing, the combined phenolphthalein/tetramethyl benzidine presumptive test for the presence of blood was conducted in the laboratory on samples recovered from the structure in an effort to assess the effectiveness of using this type of testing as a screening tool. Test results demonstrated that reliance on obtaining a positive presumptive result for blood before proceeding with DNA testing could result in the failure to obtain useful typing results. Finally, two DNA recovery methods (swabbing the stain plus cutting or scraping the stain) were attempted to evaluate their performance in recovering samples in an arson investigation. Recovery of DNA was more successful in some instances with the swabbing method, and in other instances with the cutting/scraping method. Therefore, it is recommended that both methods be used. For the most part, the recovered DNA seemed to be unaffected by the heat, until the temperature was 800°C or greater. At this temperature, no DNA profiles were obtained.     

A method for impregnating nylon transfer membranes with leucocrystal violet for enhancing and lifting bloody impressions

The objective of this research project was to demonstrate a quick and easy method for impregnating nylon transfer membranes with leucocrystal violet (LCV) for the purpose of lifting and enhancing impressions made in blood. A stamp that would simulate fine detail found in fingerprints or footwear was used to create impressions on a variety of substrates. Four different LCV formulations were tested to determine the effectiveness of the prepared membranes in lifting and enhancing the impressions. Further investigation involved the feasibility of using the LCV membranes in the field by studying the shelf life and storage of the impregnated membranes and the longevity of the lifted impressions. One of the formations studied demonstrated superior lifting and enhancing capabilities, as well as a prolonged shelf life and a resilience of the lifted impressions, thus proving LCV to be an extremely valuable technique.