Forensically Relevant Flesh Flies (Diptera, Sarcophagidae, Sarcophaginae) of Southern Brazil

Flesh flies comprise a large fly family distributed worldwide that has great importance for forensic entomology. A robust and updated checklist of Sarcophaginae flies recorded in Southern Brazil is presented, based on material collected in the Rio Grande do Sul state and on a literature review. The forensic importance (high, moderate, or none) of the recorded flesh flies for estimating the postmortem interval (PMI) or inferring cases of neglect was determined based on their ecological habits. A total of 2,831 specimens representing 38 taxa were collected from three studies. Oxysarcodexia was the most abundant and species-rich genus in all three studies. Dexosarcophaga carvalhoi (Lopes) was registered for the first time in Southern Brazil. The checklist for Southern Brazil comprises 91 species distributed in 19 genera, with Oxysarcodexia, Peckia, and Lepidodexia representing the richest genera. Considering the importance of species for PMI estimation, 10, 42, and 39 species were classified as having high, moderate, or no forensic relevance, respectively. Moreover, five myiasis-causing sarcophagine flies recorded in Southern Brazil were considered to have the potential to reveal cases of neglect or mistreatment. This study revealed that Microcerella halli (Engel) and Peckia (Euboettcheria) australis (Townsend) are the most important species for PMI estimation in Southern Brazil, as they are often found breeding in corpses in this region.

Estimating the Postmortem Interval of Carcasses in the Water Using the Carrion Insect, Brain Tissue RNA, Bacterial Biofilm, and Algae

The accurate estimation of postmortem interval (PMI) is crucial in the investigation of homicide cases. Unlike carcasses on land, various biological and abiotic factors affect the decomposition of carcasses in water. In addition, the insect evidence (e.g., blow flies) that is commonly used to estimate the PMI are unavailable before the carcasses float on water. Therefore, it is difficult to estimate the PMI of a carcass in water. This study aimed to explore an effective way of estimating the PMI of a carcass in water. Carrion insects, brain tissue RNA, bacterial biofilm on the skin surface, and algae in water with PMI were studied using 45 rat carcasses in a small river. The results showed that carrion insects might not be suitable for the estimation of PMI of a carcass in water since they do not have a regular succession pattern as a carcass on land, and the flies only colonized six of the carcasses. The target genes (β-actin, GAPDH, and 18S) in the brain tissue were associated with the PMI in a time-dependent manner within 1 week after death. A polynomial regression analysis was used to assess the relationship between the gene expression profiles and PMI. The correlation coefficient R2 of each regression equation was ≥ 0.924. A third-generation sequencing analysis showed that the bacteria on the skin surface of the carcass and the algae in the water samples around the carcass had a regular succession pattern, where Cryptomonas and Placoneis incased and decreased, respectively, within first 9 days. The results of this study provide a promising way to use the brain tissue RNA, bacterial biofilm, and algae to estimate the PMI of a carcass in water.

FORENSIC MEDICAL ASSESSMENT OF MORPHOLOGICAL CHANGES AT DIFFERENT POSTMORTEM INTERVAL

Purpose: The postmortem interval (PMI) evaluation is one of priorities while performing a forensic medical examination of corpse. To date, there is lack of information of morphological postmortem changes of some internal organs. Considering the persistent need to develop the method for a precise assessment of PMI, postmortem changes in these potentially informative organs were evaluated. The aim of study was to analyze morphological postmortem changes in prostate and uterus. Materials and Methods: histological samples of 40 prostate tissues and 40 uterus (n=80) from corpses of deceased aged 18-75 years. Only cases with known time of death were included to study, the time of death was taken from police reports. Exclusion criteria were cases of violent death, cases of death with massive blood loss, tumors of studied internal organs, cases when diagnosis was not made by a forensic medical examiner. The PMI of studied cases ranged from 1 to 6 days. Histological slides were made with a staining by hematoxylin and eosin, x200 magnification, using Olympus ВХ41 and Olympus ВХ46 microscopes, Olympus SC50 camera. Postmortem morphological changes were evaluated by a calculation of blank spaces percentage in microscopical structures using a JS-based program. Connection between PMI and morphological changes was calculated by the Spearman’s rank correlation. Results: the average percentage of blank spaces in uterus tissues was smaller than in prostate tissues (1,99 and 9,65 relatively). The slower growing of blank spaces was in uterus. In prostate samples, a notable increase of blank spaces was observed between 48 and 72 hours after the death. After this period, the increase slowed down and then an increase was observed again between 120 and 144 hours after the death. In uterus samples, a slight acceleration observed between 72 and 120 hours after the death and then slowing down between 120 and 144 hours after the death. Blank spaces in evaluated histological slides were increasing directly proportional to the PMI, a statistically significant interconnection was defined (p < 0.05). Conclusions: The morphological postmortem changes in prostate and uterus were developing at certain time frames. Blank spaces percentage, in studied histological slides, were increasing directly proportional to the PMI increase, a statistically significant interconnection was defined. Therefore, the results of study show the possibility of the evaluation of a postmortem time interval by assessing such morphological changes in these organs, which could be used in forensic medical cases.

Research progress in the estimation of postmortem interval (PMI) using non-coding RNA (ncRNA) markers

Postmortem interval (PMI) estimation has always been a crucial focus and challenging issue in forensic pathology. In recent years, specific RNA molecules and their variation have been used worldwide to estimate PMI. In this review, we summarize the methods used to detect non-coding RNAs (ncRNAs) for PMI estimation based on the literature, show the existing problems and development trends, and provide technical references for relevant studies and estimation practices.

A Preliminary Study of Necrophagous Flies (Insecta: Diptera) in the Lhasa Region (Qinghai–Tibet Plateau), China

Lhasa is located on the Qinghai–Tibet Plateau, with an altitude of 3,650 m, and a unique geography. Its climate is dry and cold all year round. Forensic entomological studies of the region are scarce. In this study, the diversity and seasonality of necrophagous flies in eight counties among Lhasa region were determined, and succession of necrophagous flies colonizing on rabbits in the Chengguan area of Lhasa was studied, so as to provide reference data for estimating postmortem interval (PMI) and location of death. In total, 22 species of necrophagous flies, belonging to six families were identified in Lhasa. Protophormia terraenovae (Robineau-Desvoidy, 1830) (Diptera: Calliphoridae) was the dominant species throughout the year, the diversity index (4.5834) indicated that the study on necrophagous flies in the Lhasa region is representative.

Determination of Postmortem Interval by Estimating CSF Proteins Concentration after Death, by Dye Binding Method at a Tertiary Care Hospital in Lahore, Pakistan

Introduction: Postmortem interval (PMI) is the time lapse between death of a person and its postmortem examination i.e. autopsy. Estimating the postmortem interval (PMI) is an imperative perspective of forensic medicine. Aims & Objectives: This study was conducted to see the impact of CSF protein estimation on determination of PMI. Place and duration of study: It was an observational correlational study, conducted for one year at Department of Forensic Medicine, King Edward Medical University Lahore. Material & Methods: A total of 119 cadavers were included in this study. Chemicals used were disodium molybdate, pyrogallol, succinic acid. The minimum detectable concentration of total proteins in CSF with dye binding method using pyrogallol red was determined as 0.022g/l. Two ml of CSF was taken from each cadaver. Clear, colorless samples were taken in test tubes. Turbid and blood contained samples were not included in study. Protein concentration was determined using photospectrometry. Statistical analysis was done by SPSS-23. Quantitative variables like age were presented as mean ± SD. Qualitative variables like gender were presented as frequency and percentages. For comparison between PMI and CSF proteins concentration correlation was applied. Results: Males accounted for majority of our subjects. The mean value of proteins in CSF was 219.91± 113.121 mg/dl. The most common PMI was 11 to 20 hours. CSF proteins increased gradually over 72 hours after death. The results of present study showed a significant positive correlation between time of death and CSF proteins concentration after death. Conclusion: It is observed that as a whole protein concentration increased with increasing time of death. Hence, CSF protein concentration can be used in estimating time since death.

A comparative study of pleural effusion in water area, water temperature and postmortem interval in forensic autopsy cases of drowning

Japan is surrounded by the sea and is also a mountainous country with many rivers. Japan has the second- highest rate of deaths caused by drowning in the world. Pleural effusion (PE) is one of the major findings at autopsy. It is found in approximately 80% of drowning mortalities and is observable for a relatively long postmortem interval (PMI). We focused on the amount of pleural fluid in drowning cases, discussed the relationship of PE with the drowning environment, water temperature, and postmortem interval, and established more simple and practical criteria for the diagnosis of drowning. We measured the weight of the lungs, PE, and their sum as the intrathoracic (IT) weight (total weight of lungs + pleural effusion), and calculated the PE ratio [(PE weight/IT weight) × 100]. A total of 130 drowning deaths diagnosed through forensic autopsies were investigated in this study. The cases were classified by drowning environment (freshwater, brackish water, and seawater), water temperature (under 20 °C, more than 20 °C), and postmortem interval (less than 1 day, 1–3 days, more than 3 days). The present study demonstrated that the PE ratio may be more effective for the diagnosis of drowning. Moreover, the accumulation of PE is affected by drowning environment, water temperature, and PMI. Collectively, it is important to assess the PE ratio and consider these factors in autopsy cases of victims found in water.