The Effect of Clothing on the Rate of Decomposition and Diptera Colonization on Sus scrofa Carcasses

Twenty Sus scrofa carcasses were used to study the effect the presence of clothing had on decomposition rate and colonization locations of Diptera species; 10 unclothed control carcasses were compared to 10 clothed experimental carcasses over 58 days. Data collection occurred at regular accumulated degree day intervals; the level of decomposition as Total Body Score (TBS_surf), pattern of decomposition, and Diptera present was documented. Results indicated a statistically significant difference in the rate of decomposition, (t₄₂₇ = 2.59, p = 0.010), with unclothed carcasses decomposing faster than clothed carcasses. However, the overall decomposition rates from each carcass group are too similar to separate when applying a 95% CI, which means that, although statistically significant, from a practical forensic point of view they are not sufficiently dissimilar as to warrant the application of different formulae to estimate the postmortem interval. Further results demonstrated clothing provided blow flies with additional colonization locations.     

Assessing three soil removal methods for environmental DNA analysis of mock forensic geology evidence

Soil is useful in criminal investigations as it is highly variable and readily transferred. Forensic geologists use several different techniques to removal soil from evidence prior to the analysis of inorganic components. There has been recent interest from the forensic science community to analyze environmental deoxyribonucleic acid (eDNA) associated with soil to augment existing forensic analyses. Notably however, limited research has been conducted to compare commonly used soil removal methods for downstream eDNA analysis. In this study, three soil removal methods were assessed: picking/scraping, sonication, and swabbing. Three mock evidence types (t-shirts, boot soles, and trowels) were sampled in triplicate with each removal method (n = 27). Soil samples underwent DNA isolation, quantification, and amplification of four genomic barcode regions: 16S for bacteria, ITS1 for fungi, ITS2 for plants, and COI for arthropods. Amplicons were prepared into libraries for DNA sequencing on an Illumina^® MiniSeq. DNA concentrations were highest in picked/scraped samples and were statistically significant compared with swabbed and sonicated samples. Amplicon sequence variants (ASVs) were identified, and removal methods had no impact on the recovery of the total number of target ASVs. Additionally, when assessing each sample in multidimensional space, picked/scraped samples tended to cluster separately from swabbed and sonicated samples. The soil core used a reference in this study also clustered with the picked/scraped samples, indicating that these samples may be more reflective of the communities collected from soil cores. Based on these data, we identified that picking/scraping is an acceptable soil removal method for eDNA analysis.     

Whole Plastome Sequences of Two Drug-Type Cannabis: Insights Into the Use of Plastid in Forensic Analyses

DNA is one of the fastest growing tools in forensic sciences, increasing reliability in forensic reports and judgments. The use of DNA has increased in different areas of the forensic sciences, such as investigation of plant species, where plastid DNA has been used to elucidate and generate evidence in cases of traceability of genetically modified and controlled plants. Even with several advances and the practice of using DNA in forensic investigations, there are just few studies related to the identification of genetic tools for the characterization of drug and nondrug-types of Cannabis. Herein, the whole plastomes of two drug-type Cannabis are presented and have their structures compared with other Cannabis plastomes deposited in the GenBank, focusing in the forensic use of plastome sequences. The plastomes of Cannabis sativa “Brazuka” and of the hybrid Cannabis AK Royal Automatic presented general structure that does not differs from the reported for other C. sativa cultivars. A phylogenomic analyses grouped C. sativa “Brazuka” with the nondrug C. sativa cultivars, while the hybrid Cannabis AK Royal Automatic placed isolated, basal to this group. This suggests that the analysis of plastomes is useful toward genetic identification of hybrids in relation to C. sativa.     

Strengths,Limitations, and Recommendations for Instrumental Color Measurement in Forensic Soil Characterization

Color determination of soil evidence is often done by visual comparison to soil color charts. A handheld spectrophotometer was tested with representative materials for its suitability for forensic soil characterization. Instrumental colorimetry provides accurate colorimetry with ~10-fold better precision than a soil color chart. The minimum sample size for accurate color determination was between 0.02 and 0.04 mg of fine soil for the specific instrument tested. Reporting colors in the L*a*b* space permits quantification of ΔE₀₀, a measure of perceptible color difference, could enable objective quantification of small color differences and thresholds for forensic soil comparisons. A ΔE₀₀ greater than ~ 3.5 to 6 likely indicates disparate soil sources in a forensic comparison, in the absence of confounding factors like sample alteration. Despite the superior precision of instrumental colorimetry, this approach is inappropriate for samples which are mottled at an inseparable scale, attached to a substrate, or too small for instrumental measurement.     

DNA Barcoding Identifies all Immature Life Stages of a Forensically Important Flesh Fly (Diptera: Sarcophagidae)

Carrion‐breeding insects, such as flesh flies (Diptera: Sarcophagidae), can be used as evidence in forensic investigations. Despite their considerable forensic potential, their use has been limited because morphological species identification, at any life stage, is very challenging. This study investigated whether DNA could be extracted and cytochrome oxidase subunit I (COI) barcode sequences obtained for molecular identification of each immature life stage of the forensically important Australian flesh fly, Sarcophaga (Sarcorohdendorfia) impatiens (Walker). Genomic DNA extracts were prepared from all larval instars and puparia. Amplification of the barcoding region was successful from all extracts, but puparia amplicons were weak. All sequences were identified as S. impatiens with 99.95% confidence using the Barcoding of Life Database (BOLD). Importantly, crop removal was necessary to eliminate PCR inhibition for specimens from late second and early third instars. Similar results are expected for immatures of other carrion‐breeding species, enhancing the use of evidence from immature flies in forensic investigations.     

The Influence of Penetrative Trauma on the Rate of Decomposition*†

Abstract: An understanding of the factors affecting decomposition is important for the accurate estimation of postmortem interval. An experimental study on the influence of penetrating trauma on decomposition rate was carried out using the domestic pig, Sus scrofa. The results of this study were: (i) Diptera were preferentially attracted to and oviposited at natural orifices. Trauma sites were not preferentially selected for oviposition; (ii) no differences between trauma and non‐trauma groups were found in time to skeletonization, weight loss (p = 0.906), total body score (p = 0.824), body temperature (p = 0.967), or changes in soil pH (p = 0.684); and (iii) the effect of investigator disturbance was significant when decomposition was measured as weight loss (p = 0.000). This study suggests that penetrating trauma of the type used in this study cannot be considered a major factor in the rate of decomposition and time to skeletonization of a gunshot trauma victim.     

A Checklist of Calliphoridae Blowflies (Insecta,Diptera) Associated with a Pig Carrion in Central Brazil*

Abstract: Although the Cerrado is the second major Brazilian biome, few studies have been undertaken about its entomofauna. Blowflies have an important role in forensic entomology, helping in the determination of postmortem intervals. The main goal of this exploratory study was to identify and to catalog the blowfly species associated with a pig carcass. The study was conducted in a pasture in Brasília, Distrito Federal. A pig (Sus scrofa) was killed with a .22 caliber shot in the frontal region of the head. Adult blowflies were surveyed daily from June 1 through 30, 2004. A total of 14,910 adult calliphorids were collected, representing eight species: Chrysomya albiceps, C. megacephala, Cochliomyia macellaria, Chloroprocta idioidea, Hemilucilia semidiaphana, H. segmentaria, Lucilia cuprina, and L. eximia. C. albiceps was the most frequent species, amounting to 94.76% of the catch. Five decomposition stages were observed, and for calliphorids, the most attractive stage was the bloated one.     

An Evidence‐Based Forensic Taxonomy of Windows Phone Communication Apps

Communication apps can be an important source of evidence in a forensic investigation (e.g., in the investigation of a drug trafficking or terrorism case where the communications apps were used by the accused persons during the transactions or planning activities). This study presents the first evidence‐based forensic taxonomy of Windows Phone communication apps, using an existing two‐dimensional Android forensic taxonomy as a baseline. Specifically, 30 Windows Phone communication apps, including Instant Messaging (IM) and Voice over IP (VoIP) apps, are examined. Artifacts extracted using physical acquisition are analyzed, and seven digital evidence objects of forensic interest are identified, namely: Call Log, Chats, Contacts, Locations, Installed Applications, SMSs and User Accounts. Findings from this study would help to facilitate timely and effective forensic investigations involving Windows Phone communication apps.     

The Role of Forensic Botany in Crime Scene Investigation: Case Report and Review of Literature

Management of a crime is the process of ensuring accurate and effective collection and preservation of physical evidence. Forensic botany can provide significant supporting evidences during criminal investigations. The aim of this study is to demonstrate the importance of forensic botany in the crime scene. We reported a case of a woman affected by dementia who had disappeared from nursing care and was found dead near the banks of a river that flowed under a railroad. Two possible ways of access to crime scene were identified and denominated “Path A” and “Path B.” Both types of soil and plants were identified. Botanical survey was performed. Some samples of Xanthium Orientalis subsp. Italicum were identified. The fall of woman resulted in external injuries and vertebral fracture at autopsy. The botanical evidence is important when crime scene and autopsy findings are not sufficient to define the dynamics and the modality of death.     

Preliminary Observations of Arthropods Associated with Buried Carrion on Oahu

Several studies in Hawaii have focused on arthropod succession and decomposition patterns of surface remains, but the current research presents the first study to focus on shallow burials in this context. Three domestic pig carcasses (Sus scrofa L.) were buried at the depths of 20–40 cm in silty clay loam soil on an exposed ridge on the leeward side of the volcanically formed Koolau Mountain Range. One carcass was exhumed after 3 weeks, another after 6 weeks, and the last carcass was exhumed after 9 weeks. An inventory of arthropod taxa present on the carrion and in the surrounding soil and observations pertaining to decomposition were recorded at each exhumation. The longer the carrion was buried, the greater the diversity of arthropod species that were recovered from the remains. Biomass loss was calculated to be 49% at the 3‐week interval, 56% at the 6‐week interval, and 59% at the 9‐week interval.     

Comparison of Protocols for Measuring and Calculating Postmortem Submersion Intervals for Human Analogs in Fresh Water

Protocols for determining postmortem submersion interval (PMSI) have long been problematic for forensic investigators due to the wide variety of factors affecting the rate of decomposition of submerged carrion. Likewise, it has been equally problematic for researchers to develop standardized experimental protocols to monitor underwater decomposition without artificially affecting the decomposition rate. This study compares two experimental protocols: (i) underwater in situ evaluation with photographic documentation utilizing the Heaton et al. total aquatic decomposition (TAD) score and (ii) weighing the carrion before and after submersion. Complete forensic necropsies were performed as a control. Perinatal piglets were used as human analogs. The results of this study indicate that in order to objectively measure decomposition over time, the human analog should be examined at depth using the TAD scoring system rather than utilizing a carrion weight evaluation. The acquired TAD score can be used to calculate an approximate PMSI.     

Human Versus Animal: Contrasting Decomposition Dynamics of Mammalian Analogues in Experimental Taphonomy

Taphonomic studies regularly employ animal analogues for human decomposition due to ethical restrictions relating to the use of human tissue. However, the validity of using animal analogues in soil decomposition studies is still questioned. This study compared the decomposition of skeletal muscle tissues (SMTs) from human (Homo sapiens), pork (Sus scrofa), beef (Bos taurus), and lamb (Ovis aries) interred in soil microcosms. Fixed interval samples were collected from the SMT for microbial activity and mass tissue loss determination; samples were also taken from the underlying soil for pH, electrical conductivity, and nutrient (potassium, phosphate, ammonium, and nitrate) analysis. The overall patterns of nutrient fluxes and chemical changes in nonhuman SMT and the underlying soil followed that of human SMT. Ovine tissue was the most similar to human tissue in many of the measured parameters. Although no single analogue was a precise predictor of human decomposition in soil, all models offered close approximations in decomposition dynamics.     

Comparing the Scoring of Human Decomposition from Digital Images to Scoring Using On‐site Observations

When in forensic casework or empirical research in‐person assessment of human decomposition is not possible, the sensible substitution is color photographic images. To date, no research has confirmed the utility of color photographic images as a proxy for in situ observation of the level of decomposition. Sixteen observers scored photographs of 13 human cadavers in varying decomposition stages (PMI 2–186 days) using the Total Body Score system (total n = 929 observations). The on‐site TBS was compared with recorded observations from digital color images using a paired samples t‐test. The average difference between on‐site and photographic observations was ?0.20 (t = ?1.679, df = 928, p = 0.094). Individually, only two observers, both students with <1 year of experience, demonstrated TBS statistically significantly different than the on‐site value, suggesting that with experience, observations of human decomposition based on digital images can be substituted for assessments based on observation of the corpse in situ , when necessary.     

Arthropods of Forensic Importance on Pig Carrion in the Coahuilan Semidesert,Mexico

Abstract: This is the first report of an ongoing research to establish a sarcosaprophagous arthropod database in the Coahuilan semidesert. Seven pigs (Sus scrofa L.) were used as human models to determine succession in an open urban area during the 2007 winter–spring period. Arthropods were collected manually and from pitfall traps. Carcass biomass loss, as well as arthropod colonization, was recorded during 71 days postmortem. Five decomposition stages were identified during which most abundant orders were found to be Diptera, Coleoptera, and Hymenoptera. Lucilia sericata (Meigen), Chrysomya rufifacies (Macquart), Necrobia rufipes (DeGeer), Dermestes maculatus (DeGeer), Pheidole hyatti Emery, and Pogonomyrmex rugosus Emery stood out as dominant species.     

A Three‐Locus,PCR‐based Method for Forensic Identification of Plant Material

Plant residue is currently an underutilized resource in forensic investigations despite the fact that many crime scenes, as well as suspects and victims, harbor plant‐derived residue that could be recovered and analyzed. Notwithstanding the considerable skill of forensic botanists, current methods of species determination could benefit from tools for DNA‐based species identification. However, DNA barcoding in plants has been hampered by sequence complications in the plant genome. Following a database search for usable barcodes, broad‐spectrum primers were designed and utilized to amplify and sequence the rbcL, trnL‐F, and rrn18 genetic loci from a variety of household plants. Once obtained, these DNA sequences were used to design species‐targeted primers that could successfully discriminate the source of plant residue from among the 21 species tested.     

Identification of Bodies by Unique Serial Numbers on Implanted Medical Devices

Visual identification is the most common identification method used by medical examiners but is not always possible. Alternative methods include X‐ray, fingerprint, or DNA comparison, but these methods require additional resources. Comparison of serial numbers on implanted medical devices is a rapid and definitive method of identification. To assess the practicality of using this method, we reviewed 608 consecutive forensic autopsies performed at a regional medical examiner office. Of these, 56 cases required an alternative method of identification due to decomposition (n = 35), gunshot wound (n = 9), blunt trauma (n = 6), or charring (n = 6). Of these 56 cases, eight (14.3%) were known to have an implanted medical device. Of these eight cases, five (63%) could be positively identified by comparing serial numbers. If an implanted medical device is known to be present, and medical records are available, identification by medical device serial number should be a first‐line method.     

Volatile Organic Compound Profiling from Postmortem Microbes using Gas Chromatography–Mass Spectrometry

Volatile organic compounds (VOCs) are by-products of cadaveric decomposition and are responsible for the odor associated with decomposing remains. The direct link between VOC production and individual postmortem microbes has not been well characterized experimentally. The purpose of this study was to profile VOCs released from three postmortem bacterial isolates (Bacillus subtilis, Ignatzschineria indica, I. ureiclastica) using solid-phase microextraction arrow (SPME Arrow) and gas chromatography–mass spectrometry (GC-MS). Species were inoculated in headspace vials on Standard Nutrient Agar and monitored over 5 days at 24°C. Each species exhibited a different VOC profile that included common decomposition VOCs. VOCs exhibited upward or downward temporal trends over time. Ignatzschineria indica produced a large amount of dimethyldisulfide. Other compounds of interest included alcohols, aldehydes, aromatics, and ketones. This provides foundational data to link decomposition odor with specific postmortem microbes to improve understanding of underlying mechanisms for decomposition VOC production.     

Searching the Soil: Forensic Importance of Edaphic Fauna After the Removal of a Corpse

Abstract: Arthropods at different stages of development collected from human remains in an advanced stage of decomposition (following autopsy) and from the soil at the scene are reported. The corpse was found in a mixed deciduous forest of Biscay (northern Spain). Soil fauna was extracted by sieving the soil where the corpse lay and placing the remains in Berlese–Tullgren funnels. Necrophagous fauna on the human remains was dominated by the fly Piophilidae: Stearibia nigriceps (Meigen, 1826), mites Ascidae: Proctolaelaps epuraeae (Hirschmann, 1963), Laelapidae: Hypoaspis (Gaeolaelaps) aculeifer (Canestrini, 1884), and the beetle Cleridae: Necrobia rufipes (de Geer, 1775). We confirm the importance of edaphic fauna, especially if the deceased is discovered in natural environs. Related fauna may remain for days after corpse removal and reveal information related to the circumstances of death. The species Nitidulidae: Omosita depressa (Linnaeus, 1758), Acaridae: Sancassania berlesei (Michael, 1903), Ascidae: Zerconopsis remiger (Kramer, 1876) and P. epuraeae, Urodinychidae: Uroobovella pulchella (Berlese, 1904), and Macrochelidae: Glyptholaspis americana (Berlese, 1888) were recorded for the first time in the Iberian Peninsula.     

Diel Activity and Effect of Carcass Decomposition on the Attractiveness to the Forensically Important Species Oxelytrum Discicolle (Coleoptera: Silphidae)†

Oxelytrum discicolle is a carrion beetle commonly found in the Neotropical region, mainly associated with cadavers and carcasses. Information on behavior related to the likelihood of cadaver colonization is scarce. We performed two field experiments in peri‐urban forest in Brazil in order to strengthen our knowledge on O. discicolle behavior. In the first experiment, we assessed the preference for piglet carcasses at different stages of decomposition offered simultaneously in two seasons, dry and rainy, while in the second experiment we investigated the diel activity of adults. A total of 493 adults were collected in the experiments. A significantly higher abundance was detected in the rainy season. There was a marked preference for carcasses at advanced stages. Adults exhibited a typical nocturnal behavior, the number trapped at night was 17 times greater than those collected during the day. Oxelytrum discicolle is nocturnal species that prefers carcasses in advanced stage of decomposition.