Investigation of Drowning Deaths: A Practical Review

Drowning incidents precipitated by unusual causes (DIPUCs): A narrative review of their diagnoses, evaluation and management

Drowning is a cause of significant morbidity and mortality worldwide. In most circumstances, the proximate cause is attributable to human factors, such as inexperience, fatigue, intoxication, or hazardous water conditions. The phenomenon of drowning incidents precipitated by unusual circumstances (DIPUCs) - either fatal or nonfatal - involving otherwise healthy individuals under generally safe conditions has not been comprehensively addressed in the medical and drowning literature to date. In this review, we discuss etiologies of DIPUCs, diagnostic clues, suggested workup, suggested postmortem testing, and implications for surviving patients and families. Identifying the cause of a drowning incident can be extremely challenging for the initially treating physician, relying perforce on historical context, environmental clues, physical exam, medical history, eyewitness accounts or video recordings. If no clear explanation for a drowning incident emerges despite a thorough investigation, clinicians should consider some of the less common diagnoses we describe in this paper, and, when appropriate, refer for an autopsy with postmortem molecular genetic testing. While time-consuming, these efforts can prove life-saving for some non-fatal drowning victims and the families of all victims of DIPUCs.

"Not everything that can be counted counts" in ethanol toxicological results: an antemortem and postmortem technical interpretation focusing on driving under the influence

Ethanol blood analysis is the most common request in forensic toxicology, and some studies point to positive results in approximately one-third of all unnatural deaths. However, distinguishing sober deaths from drunk deaths is not as simple as it may seem. This technical, clinical, and forensic interpretation is proposed to interpret the ethanol toxicological results, discussing several artefacts and pitfalls that must be considered, namely focusing on driving under the influence. This work is presented with a practical and objective approach, aiming to alleviate the complexities associated with clinical, physiological, pathophysiological, and toxicological aspects to enhance comprehension, practicality, and applicability of its content, especially to courts. Particularly the physical integrity of the body, the postmortem interval, putrefactive signs, anatomic place of blood collection, alternative samples such as vitreous humour and urine, the possibility of postmortem redistribution, the inclusion of preservatives in containers, and optimal temperature conditions of shipment are among some of the aspects to pay attention. Although several biomarkers related to postmortem microbial ethanol production have been proposed, their translation into forensic routine is slow to be implemented due to the uncertainties of their application and analytical difficulties. Specifically, in the interpretation of ethanol toxicological results, "not everything that can be counted counts and not everything that counts can be counted" (attributed to Albert Einstein).

Development and Validation of a Bayesian Network Predicting Intubation Following Hospital Arrival Among Injured Children

BACKGROUND

Inadequate airway management can contribute to preventable trauma deaths. Current machine learning tools for predicting intubation in trauma are limited to adult populations and include predictors not readily available at the time of patient arrival. We developed a Bayesian network to predict intubation in injured children and adolescents using observable data available upon or immediately after patient arrival.

METHODS

We obtained patient demographic, injury, resuscitation, and transportation characteristics from trauma registries from four American College of Surgeons-verified level 1 pediatric trauma centers from January 2010 through December 2021. We trained and validated a Bayesian network to predict emergent intubation after pediatric injury. We evaluated model performance using the area under the receiver operating and calibration curves.

RESULTS

The final model, TITAN (Timing of Intubation in Trauma Analysis Network), incorporated five factors: Glasgow Coma Scale, mechanism of injury, injury type (e.g., penetrating, blunt), systolic blood pressure, and age. The model achieved an area under the receiver operating characteristic curve of 0.83 (95% CI 0.80, 0.85) and had a calibration curve slope of 0.98 (95% CI 0.67, 1.29). TITAN had high specificity (98%), negative predictive value (97%), and accuracy (96%) at a binary probability threshold of 22.6%.

CONCLUSION

The TITAN Bayesian network predicts the risk of intubation in pediatric trauma patients using five factors that are observable early in trauma resuscitation. Prospective validation of the model performance with patient outcomes is needed to assess real-life application benefits and risks.

LEVEL OF EVIDENCE

Prognostic and Epidemiological, Level III.

The use of dive computers in forensic investigations of fatal breath-hold diving accidents: a case study

Freediving is a type of diving in which divers rely solely on how long they can hold their breath underwater during their dive, which is why it can also be referred to as 'breath-hold diving'. Unlike scuba (self-contained underwater breathing apparatus) diving, individuals do not require training or licencing to perform freediving and may not be aware of the risks of this activity. This paper presents a case in which coastguards retrieved a free diver's lifeless body from the seafloor. In most cases such as this, the deceased individual's cause of death would be ruled as drowning. With the deceased diver's dive computer, we concluded that a shallow water blackout caused him to drown. Data from the dive computer were extracted, graphed, and analysed to explain how a skilled swimmer and diver drowned on one of his seemingly ordinary diving trips. The dive computer can be the sole witness to a fatal dive event and provide invaluable information to forensic scientists since the diver is almost always alone. To our knowledge of the available literature, dive computers have been used in scuba diving fatality investigations; however, we believe that they have not been used in death investigations of breath-hold divers. Deficient or hasty conclusions are often based solely on autopsy findings without data collected by diving technicians and investigators. It is crucial to wait to draw conclusions until all possible dive information has been gathered and studied. This study discusses the deficiency in presenting a reasonable idea to the grieving family and friends of how their beloved relative could have drowned even though he was known to be a fit and skilled diver and avid swimmer.

Water-related fatalities: An examination of body displacement and recovery patterns in British Columbia, Canada

Early recovery of human bodies from the water requires an understanding of how a body acts in the water. However, there is currently a lack of baseline data surrounding body movement in British Columbian (B.C.) waters. This study aims to assist Canadian response agencies with understanding and predicting body movement in outdoor waterbodies in B.C. One hundred and eighty-six water-related fatalities in B.C. waters, including lakes, rivers, and the coastal Pacific Ocean, were examined to determine the recovery times and displacement patterns of submerged decedents. Cases between 2010 and 2021 were extracted from the Police Records Information Management Environment (PRIME-BC) for analysis. Most deaths were unintentional, followed by suicide and homicide, and most often occurred in rivers, followed by lakes and the ocean. Regardless of waterbody, the first day was the most successful recovery period, with decedents most often recovered close to the incident location. Nearly 16% of individuals in this study were not recovered. Recovery success was greatest in lakes, followed by rivers and the ocean. Body displacement was the least in lakes, while rivers resulted in the furthest and most variable displacement. Low recovery success in the ocean is likely due to decedents being quickly displaced out of the search area, never to be found. The results of this study suggest that knowledge of body movement in outdoor aquatic environments remains incomplete. Further empirical research based on known data is necessary to continue improving prediction of body movement and increase early recovery success.

Five-year review (2014-2019) of paediatric accidental deaths in Cook County, Illinois (USA)

In the USA, intentional and accidental injuries are the most frequent causes of death in children. Many of these deaths could be avoided through preventive measures, and aetiological studies are needed to reduce fatalities. The leading causes of accidental death vary by age. We analysed all paediatric accidental deaths recorded by a busy urban Medical Examiner"s Office in Chicago, Illinois (USA). We searched the electronic database for accidental deaths in children aged under 10 between 1 August 2014 and 31 July 2019. 131 deaths were identified with a preponderance of males and African Americans. This is consistent with ratios of other deaths recorded for this age group (during the same period and area). The leading causes of death were asphyxia due to an unsafe sleeping environment (in subjects <1-year-old), and road traffic accidents/drowning (in subjects >1-year-old). Behaviours, risk factors and environments most likely to contribute to fatal injuries are discussed. Our study highlights the role of forensic pathologists and medico-legal death investigators who identify the causes and circumstances surrounding these deaths. The research results may help from an epidemiological perspective to implement age-specific preventive strategies.

Termination of Cardiopulmonary Resuscitation in Mountain Rescue: A Scoping Review and ICAR MedCom 2023 Recommendations

Lugnet, Viktor, Miles McDonough, Les Gordon, Mercedes Galindez, Nicolas Mena Reyes, Alison Sheets, Ken Zafren, and Peter Paal. Termination of cardiopulmonary resuscitation in mountain rescue: a scoping review and ICAR MedCom 2023 recommendations. High Alt Med Biol. 24:274-286, 2023. Background: In 2012, the International Commission for Mountain Emergency Medicine (ICAR MedCom) published recommendations for termination of cardiopulmonary resuscitation (CPR) in mountain rescue. New developments have necessitated an update. This is the 2023 update for termination of CPR in mountain rescue. Methods: For this scoping review, we searched the PubMed and Cochrane libraries, updated the recommendations, and obtained consensus approval within the writing group and the ICAR MedCom. Results: We screened a total of 9,102 articles, of which 120 articles met the inclusion criteria. We developed 17 recommendations graded according to the strength of recommendation and level of evidence. Conclusions: Most of the recommendations from 2012 are still valid. We made minor changes regarding the safety of rescuers and responses to primary or traumatic cardiac arrest. The criteria for termination of CPR remain unchanged. The principal changes include updated recommendations for mechanical chest compression, point of care ultrasound (POCUS), extracorporeal life support (ECLS) for hypothermia, the effects of water temperature in drowning, and the use of burial times in avalanche rescue.

Emerging issues in the approach to submerged bodies: Water-related deaths in Friuli, northeastern Italy (1993-2020). Analysis of post-mortem reports and some unusual cases

When analysing bodies recovered from a watery environment, all manners of death, a variety of causes of death and the possibility of body disposal have to be considered. Unclear circumstances of death, unidentified victims and body decomposition may hamper a forensic investigation. The lack of specific and sensitive drowning-related autopsy findings and post-mortem blood alcohol levels (blood alcohol concentrations (BACs)) may also lead to erroneous conclusions. We reviewed the autopsy records for all bodies recovered from water in Friuli, northeastern Italy, over a 28-year period, focusing on death circumstances, autopsy findings and blood alcohol levels. Some unusual cases were examined separately. Among the 69 cases, there were 32 accidents, 13 suicides, 4 homicides, 6 natural and 14 undetermined deaths. Causes of death included 51 drownings, 6 undetermined, 5 cardiac deaths and 7 non-drownings. Six deaths in a bathtub and one diving-related death were also included. Acute alcohol intoxication was ascertained in 22 of 40 victims. Some significant limitations in the approach to water-related deaths have been highlighted: although emphysema aquosum and external foam resulted to be the most reliable indicators, a determination of drowning based exclusively on autopsy findings cannot be ascertained with certainty. Furthermore, it was found that the standard definitions of wet and dry drowning in the literature differ widely from a morphological perspective and this may lead to misleading outcomes. Post-mortem BAC changes have been critically analysed only in bodies found in cold water, and, in the absence of an alternative to blood specimens, the use of pre-set cut-off values is still necessary.

Applicable Forensic Biomarker for Drowning Diagnosis: Extracellular Signal-Regulated Kinase 2 (ERK2)

Drowning is a common cause of accidental death worldwide, and it continues to be a serious public health problem. However, diagnosing drowning is a challenging task in forensic investigation because it is difficult to prove actual drowning and other submerged deaths with the autopsy techniques that are currently in use. Here, we show biomarkers that may be helpful for the diagnosis of drowning. We divided the experimental animals into four groups (drowning, postmortem submersion, hypoxia, and control) to evaluate the expression patterns of extracellular signal-regulated kinase 1/2 (ERK1/2). On gene expression analysis, only ERK2 was found to be significantly increased in the drowning groups compared to the other cases. In the immunoblot analysis, phosphorylated ERK2 (p-ERK2) was found to be upregulated in the drowning groups. Immunohistochemical staining also showed that p-ERK in alveolar cells revealed a granular pattern in the drowning groups. However, the expression pattern of ERK2 over time after drowning differed between the freshwater and seawater drowning groups. Taken together, these results indicate that ERK2 may be useful for distinguishing between drowning and postmortem submersion if the postmortem interval (PMI) of drowning is short. Conversely, if the PMI is long from the time that death occurs until the discovery of dead bodies, it is possibly more helpful for identifying between freshwater and seawater drowning.

Validation and optimization of the diatom L/D ratio as a diagnostic marker for drowning

If a dead body is discovered in water, it nearly always raises the question about the cause of death, often associated with the persistent problem to differentiate between a drowning incident and post-mortem immersion. In numerous cases, a reliable confirmation of death by drowning is often only possible by a combination of diagnoses obtained from autopsy and additional investigations. As to the latter, the use of diatoms has been suggested (and debated) since decades. Based on the consideration that diatoms are present in almost every natural waterbody and are unavoidably incorporated when water is inhaled, their presence in the lung and other tissues can provide evidence of drowning. However, the traditional diatom test methods are still subject of controversial discussion and suspected of erroneous outcome, predominantly through contamination. A promising alternative to minimize the risk of erroneous outcome seems to be disclosed by the recently suggested MD-VF-Auto SEM technique. Especially the establishment of a new diagnostic marker (L/D ratio), which represents the factorial proportion between the diatom concentration in lung tissue and the drowning medium, allows for clearer distinction of drowning and post-mortal immersion and is largely robust to contamination. However, this highly elaborated technique requires specific devices which are frequently unavailable. We therefore developed a modified method of SEM-based diatom testing to enable the use on more routinely available equipment. Process steps such as digestion, filtration, and image acquisition were thoroughly broken down, optimized, and ultimately validated in five confirmed drowning cases. Taking certain limitations into consideration, L/D ratio analysis provided promising results, even in cases of advanced decomposition. We conclude that our modified protocol indeed opens a way for a broader use of the method in forensic drowning investigation.

B. G, Vijay V, Prakash M. Post-mortem freshwater animal predation—a case report

Background

Post-mortem animal predation affects human corpses in various ways. Lesions are a characteristic of the type of terrestrial or aquatic predators. These lesions can be misinterpreted and may be challenging for the forensic pathologist. Different species in freshwater cause different types of lesions depending on their feeding habits. There is a paucity in the literature about post-mortem lesions caused by freshwater animals.

Case presentation

A 24-year-old man had accidentally drowned while fishing in the River Cauvery. His body was recovered after 3 days. Though the cause of death was drowning, post-mortem animal activity was observed during autopsy, and a live juvenile crab was also found along with the body. Distinct post-mortem lesions caused by decapods Oziotelphusa wagrakarowensis and small fishes Hypselobarbus dubius and Dawkinsia arulius are described.

Conclusions

Aquatic predators and their activity on the corpse are different from that of terrestrial predators. Knowledge of the local fauna is required to correlate the lesions on the body to the predator.

Atmospheric circulation and mortality by unintentional drowning in Spain: from 1999 to 2018

AIMS

Drowning deaths are a leading cause of unintentional deaths worldwide. Few studies have analysed the role of meteorology in drowning, and with inconclusive results. The aim of this work is to analyse the temporal and geographical distribution of deaths by accidental drowning and submersion in Spain over 20 years, and to assess the relationship between accidental drowning and main atmospheric circulation patterns.

METHODS

An ecological study was performed, in which drowning and submersion mortality data from 1999 to 2018, considering demographic variables, were analysed. To study the association with atmospheric circulation we used an ERA5 reanalysis product over the whole European continent and the Climatic Research Unit Time Series (CRU TS) data set.

RESULTS

The annual average rate of deaths by accidental drownings was 11.86 deaths per million of habitants in Spain. The incidence in males was four times higher than in females, and when comparing age groups, the rate in the eldest group was the highest. Unintentional drowning deaths were not equally distributed around the country; the provinces with the highest registered standardized drowning death rates were touristic waterfront provinces either in Eastern Spain or in one of the archipelagos. There was a significant relationship between accidental drowning and meteorological variables during summer months, and drowning deaths were spatially correlated with sea-level pressure over the Mediterranean basin.

CONCLUSION

Although the mortality rate registered a statistically significant decreasing tendency over the studied period, our results must be taken into consideration to improve the prevention strategies in the country since most of these deaths are avoidable.

Microbiome analysis: An emerging forensic investigative tool

Microbial diversity's potential has been investigated in medical and therapeutic studies throughout the last few decades. However, its usage in forensics is increasing due to its effectiveness in circumstances when traditional approaches fail to provide a decisive opinion or are insufficient in forming a concrete opinion. The application of human microbiome may serve in detecting the type of stains of saliva and vaginal fluid, as well as in attributing the stains to the individual. Similarly, the microbiome makeup of a soil sample may be utilised to establish geographic origin or to associate humans, animals, or things with a specific area, additionally microorganisms influence the decay process which may be used in depicting the Time Since death. Further in detecting the traces of the amount and concentration of alcohol, narcotics, and other forensically relevant compounds in human body or visceral tissues as they also affect the microbial community within human body. Beside these, there is much more scope of microbiomes to be explored in terms of forensic investigation, this review focuses on multidimensional approaches to human microbiomes from a forensic standpoint, implying the potential of microbiomes as an emerging tool for forensic investigations such as individual variability via skin microbiomes, reconstructing crime scene, and linking evidence to individual.

The experience of drowning

Internationally, drowning is a leading cause of accidental death that features in many legal cases. In these cases, possible mitigations and the 'pain and suffering' in terms of the duration and subjective experience of drowning are often pivotal in determining levels of compensation and outcome. As a result, there is a requirement to understand the stages of the drowning process, and the duration and physiological and subjective responses associated with each stage. In this short review we focus on these issues.

Epidemiology and autopsy findings of 500 drowning deaths

INTRODUCTION

Drowning is a significant public health problem worldwide and the WHO reported that drowning is the world's third leading unintentional injury death. Nevertheless, there is still uncertainty regarding the estimate of local and global drowning deaths. In addition, the postmortem diagnosis of drowning is challenging and the physiological mechanisms of death by drowning are complex and not very well understood.

PURPOSE

To analyze a large series of bodies retrieved from the water in Connecticut (U.S.) in order to compare epidemiologic and toxicological data with those of the literature, as well as to examine the weights of the lungs and brains in drowning deaths.

MATERIAL AND METHOD

We conducted a descriptive, retrospective, population-based analysis of all bodies retrieved from the water and subjected to a forensic autopsy at the Office of the Chief Medical Examiner in Connecticut (2008-2020, n = 500). Variables collected were sex, age, date of death, location of drowning, season, type of water, cause of death, manner of death, circumstances of death, signs of decomposition, BMI, brain weight, lung weight, presence of pulmonary edema, stomach contents, and toxicological analysis.

RESULTS

The death rates of drownings in Connecticut ranges from 0.75 to 1.28/100,000/year. They occurred predominantly in males (73.4%) and most were accidents (75.6%), though this gender difference diminishes in suicides (55.4% of males). Sex distribution is also different in bathtub drownings, where women drown more frequently (67.3%). Weights of the brains (p = 0.013) and lungs (p < 0.001) were higher in saltwater drownings.

CONCLUSIONS

Drowning is more frequently an accident involving men, except for suicides where there is only a slight difference among sex. Heavy lungs and cerebral edema continue to be identified in numerous drowning deaths. These anatomic findings, however, must still be interpreted in the context of the entire case investigation. Weights of the brains and lungs are higher in salt water, although these organs' weights are mostly dependent on other variables such as BMI and decomposition.

Forensic Identification of Diving Deaths

Investigation of the cause of death during diving is one of the contents of forensic pathology. In this article, relevant foreign literature is reviewed to summarize the techniques and methods used in the identification of diving deaths, such as accident reconstruction, diving monitoring data, postmortem CT examination and gas analysis (location and quantity) in the body of the corpse, in order to provide a reference for forensic identification of such cases.

Determining child drowning mortality in the Sundarbans, India: applying the community knowledge approach

BACKGROUND

The Sundarbans in India is a rural, forested region where children are exposed to a high risk of drowning due to its waterlogged geography. Current data collection systems capture few drowning deaths in this region.

METHODS

A community-based survey was conducted in the Sundarbans to determine the drowning mortality rate for children aged 1 to 4 years and 5 to 9 years. A community knowledge approach was used. Meetings were held with community residents and key informants to identify drowning deaths in the population. Identified deaths were verified by the child's household through a structured survey, inquiring on the circumstances around the drowning death.

RESULTS

The drowning mortality rate for children aged 1 to 4 years was 243.8 per 100 000 children and for 5 to 9 years was 38.8 per 100 000 children. 58.0% of deaths were among children aged 1 to 2 years. No differences in rates between boys and girls were found. Most children drowned in ponds within 50 metres of their homes. Children were usually unaccompanied with their primary caretaker engaged in household work. A minority of children were treated by formal health providers.

CONCLUSIONS

Drowning is a major cause of death among children in the Sundarbans, particularly those aged 1 to 4 years. Interventions keeping children in safe spaces away from water are urgently required. The results illustrate how routine data collection systems grossly underestimate drowning deaths, emphasising the importance of community-based surveys in capturing these deaths in rural low- and middle-income country contexts. The community knowledge approach provides a low-resource, validated methodology for this purpose.

The use of vitreous renal chemistries in the discrimination of postmortem fresh water drowning

Background:

The World Health Organization (WHO) has estimated drowning as the leading cause of unintentional death in the world, with 372,000 deaths reported annually. Not all drowning are unintentional; some could be disguised to cover up an act of heinous criminality. This study was aimed at using some vitreous renal function biochemical parameters as a discriminant of postmortem fresh water drowning. Twelve albino rabbits constituted the sample size as validated by Mead’s formula. The study was divided into three groups; the control, postmortem-drowned and truly drowned as mimicked using an artificial fresh water pond. Vitreous humours were extracted using Coe method. The vitreous renal chemistries were analysed using diacetyl monoxime, Jaffe’s test, uricase and ion-selective electrode (ISE) methods respectively.

Result:

The mean of vitreous creatinine, urea, uric acid, Na+, K+, Cl−, Ca2+, glucose and CO2 of the control, postmortem-drowned and truly drowned groups were compared using One-way Anova (post-hoc-LSD) with the aid of SPSS Inc., Chicago, IL, USA; Version 18–21 package. The findings revealed a significant increase in concentrations of vitreous creatinine, glucose, Ca2+ and K+ of the drowned death group, whereas vitreous concentrations of CO2 and urea significantly decreased when compared to the controls and/or postmortem-drowned death.

Conclusion:

The study has shown that some of the studied vitreous biochemical parameters could be used as an ancillary tool in discriminating death due to fresh water drowning from that of disguised or postmortem-drowned death.

Macromorphological findings in cases of death in water: a critical view on "drowning signs"

Death in water is a challenging issue in forensic pathology since from natural death to homicide all circumstances of death in water are conceivable. Therefore, the correct interpretation of all abnormal autopsy findings is important. In order to determine a death by drowning, numerous internal and external signs of drowning are already described. However, these are supposed to be influenced by various factors reducing their significance and evidence. Moreover, the autopsy of water corpses often reveals further pathological findings that should not be underestimated for determining the cause of death. The aim of this study was to set frequencies of the observed drowning signs in context to the forensic literature and to identify possible influencing factors. In this study, we observed that pathological organ changes of the cardiovascular system were significantly more common in corpses after shortened (atypical) drowning processes than in classical drowned victims. Furthermore only a complete formation of external foam, immediately after the corpse’s recovery, was exclusively found in drowning victims. All other drowning signs were either also observed in non-drowning deaths in water or no information could be provided with reasonable assurance. In addition, many of the examined drowning signs were negatively affected by prolonged postmortem intervals, putrefaction, or resuscitation attempts. It can be concluded from our analysis that morbidity is an important factor in deaths in water. Morbidity can support a death by drowning in case of incidents in water. For the examined drowning signs, no high diagnostic certainty could be observed. Nevertheless, these findings can increase their diagnostic value—if forensic physicians take influencing factors into consideration.

Fatal coastal drowning incidents: A 10-year review of body recovery times in New Zealand

Despite drowning being a leading cause of unintentional injury worldwide, gaps in the data still exist. One area where limited data is available to guide lifeguards, police, search and rescue agencies, accident and forensic investigators, ocean scientists, and the coroner, is how far from the last known point (displacement) a missing person is likely to be found, and the time frame for this to occur. This lack of certainty can exacerbate the emotional toll on family, friends, and rescuers. This study aimed to describe body recovery times and displacement for fatal coastal drowning incidents in New Zealand. Using DrownBase™, the National Coronial Information System, and media reports, data were extracted for all fatal coastal-missing-person drowning incidents from 2008 to 2017. A total of 219 cases were selected. Almost all incidents involved males (92%) and minority groups (e.g., Māori and Pasifika) were over-represented. Older adults (> 42 years) were more likely to be engaged in boating, whereas for younger adults (≤ 42 years), it was swimming. Most missing persons were described as good swimmers (51%) and wearing everyday clothing (48%), yet only 4% wore a lifejacket. Most incidents were observed (63%), and rescue was attempted in 86% of cases. Most bodies (58%) were recovered within 24h, and only 15% were not found (9%) or not reported (6%). Most missing persons (64%) were either found in the same location (57%) or <1km from where they entered the water (7%). The quality of on-scene data limited some analysis, and the results of this study may not apply to all aquatic locations. Improved data collection could inform real-time predictive modelling of where and when a missing person might be found. The involvement of forensic and ocean scientists in future study design to widen applicability to these domains is also recommended. Fewer lives would be lost to drowning, however, if safer practices were adopted when recreating or working in, on, or around water.

Impact of the Human Microbiome in Forensic Sciences: a Systematic Review

Numerous studies relate differences in microbial communities to human health and disease; however, little is known about microbial changes that occur postmortem or the possible applications of microbiome analysis in the field of forensic science. The aim of this review was to study the microbiome and its applications in forensic sciences and to determine the main lines of investigation that are emerging, as well as its possible contributions to the forensic field. A systematic review of the human microbiome in relation to forensic science was carried out by following PRISMA guidelines. This study sheds light on the role of microbiome research in the postmortem interval during the process of decomposition, identifying death caused by drowning or sudden death, locating the geographical location of death, establishing a connection between the human microbiome and personal items, sexual contact, and the identification of individuals. Actinomycetaceae, Bacteroidaceae, Alcaligenaceae, and Bacilli play an important role in determining the postmortem interval. Aeromonas can be used to determine the cause of death, and Corynebacterium or Helicobacter pylori can be used to ascertain personal identity or geographical location. Several studies point to a promising future for microbiome analysis in the different fields of forensic science, opening up an important new area of research.

Proteomics in Deaths by Drowning: Diagnostic Efficacy of Apolipoprotein A1 and α-1Antitrypsin, Pilot Study

Drowning is one of the leading causes of death worldwide. The pathophysiology of drowning is complex and, sometimes, interpretation of the circumstances of death in the autopsy becomes the main source of information in its diagnosis. New advances in medical research, such as proteomics, especially in forensic pathology, are still in the development. We proposed to investigate the application of Mass Spectrometry-based technologies, to identify differentially expressed proteins that may act as potential biomarkers in the postmortem diagnosis of drowning. We performed a pilot proteomic experiment with the inclusion of two drowned and two control forensic cases. After applying restrictive parameters, we identified apolipoprotein A1 (ApoA1) and α-1 antitrypsin as differentially expressed between the two diagnostic groups. A validation experiment, with the determination of both proteins in 25 forensic cases (16 drowned and 9 controls) was performed, and we corroborated ApoA1 higher values in the drowning group, whereas α-1 antitrypsin showed lower levels. After adjusting by confounder factors, both remained as predictive independent factors for diagnosis of drowning (p = 0.010 and p = 0.022, respectively). We constructed ROC curves for biomarkers’ levels attending at the origin of death and established an ApoA1 cut-off point of 100 mg/dL. Correct classification based on the diagnosis criteria was reached for 73.9% of the cases in a discriminant analysis. We propose apolipoprotein A1 (with our cutoff value for correct classification) and α-1 antitrypsin as valuable biomarkers of drowning. Our study, based on forensic cases, reveals our proteomic approach as a new complementary tool in the forensic diagnosis of drowning and, perhaps, in clinical future implications in drowned patients. However, this is a pilot approach, and future studies are necessary to consolidate our promising preliminary data.

Transferability of Australian diatoms to clothing: Assessment of several extraction methods on different fabric types under laboratory conditions

Crime scene investigation protocols and procedures are well established when concerning terrestrial environments, but are limited when associated with aquatic environments. In aquatic contexts, the soil, sediments and microscopic algae (e.g. diatoms) may all be used as sources of trace evidence for criminal investigations. Diatoms are one such source that can be used to support the diagnosis of death by drowning and can be used to verify contact between a suspect and a specific water body. For the latter, diatoms can be collected from clothing and shoes for forensic comparisons. Over the years, there have been several methods proposed for the extraction of diatoms from clothing, however, a best practice method is yet to be established and is still open to debate. The present research represents the first investigation that evaluates four different methods for the extraction of native and common Australian diatom species from four different types of fabrics. Diatoms of two different species and shape (pennate and centric) were cultivated in stimulated experimental waters - prepared using either monocultures or mixed cultures of the selected diatoms. Diatom concentrations were set to mimic the natural population (low to bloom events) as commonly found in the Swan River Estuary of Western Australia. Cotton, denim, blend, and acrylic fabric types were placed in experimental waters. Diatom extraction was attempted using methods already proposed in the literature, these include: rinsing with ethanol (RE); rinsing with ethanol together with the application of centrifugal force (RECF); digestion with hydrogen peroxide (H); and a new method of ashing that has never been tested before (dry ash, DA). Results of this research showed that a) the type and the concentration of the mono and mix diatom mixtures significantly affects the transfer and extraction from different types of fabric; b) a noticeable extraction difference is observed between the fabrics, establishing denim, acrylic and blend fabrics as possessing the better extraction rates; c) H treatment had the highest extraction rate of diatoms; d) the application of centrifugal force on the RE method significantly improved the extraction of diatoms; e) DA is a potential method for the extraction of pennate-shaped diatoms from all of the tested fabrics, however, does have a tendency to induce modifications of the morphological structure of the diatoms. Overall, the application of different extraction methods is suggested to maximise the extraction of diatoms that would closely reflect their natural assemblage in the water body under investigation.

Structural abnormalities in the human diaphragm in drowning and hanging deaths: preliminary results

PURPOSE

Previous experiments in rats have indicated that there are histological changes in skeletal muscle in drowning deaths; these changes include muscle fibers that contain ragged red fibers (RRF). The purpose of this study was to examine whether these changes also occur in humans.

METHODS

Histologic and histochemical examinations of three muscles (diaphragm, pectoralis, and psoas) were performed on 24 cadavers with three different causes of death: 8 drowning, 8 hanging, and 8 sudden cardiac disease. Muscle samples were stained with hematoxylin-eosin, MGT, nicotinamide adenine dinucleotide-tetrazolium reductase, succinate dehydrogenase, ATPase, and acid phosphatase via standard staining procedures.

RESULTS

There were statistically significant differences in the detection of RRFs in these cohorts. Additionally, several other cytoarchitectural changes (whorled and core-like fibers) were observed in the diaphragm in the drowning cohort and to a lesser extent in the hangings. These structural abnormalities were not observed in the sudden cardiac disease deaths, thus suggesting a common mechanism for the production of these muscular changes that is not shared in the cardiac death group. The mechanism is most likely intense hypoxia and mechanical trauma of the respiratory muscles in the setting of active blood circulation with intense muscle contraction.

CONCLUSIONS

Our results confirmed that there are histological changes in the diaphragm in drownings and, to a lesser extent, in hangings.