Estimating Time Since Death from Postmortem Human Gut Microbial Communities

Postmortem succession of human‐associated microbial communities (“human microbiome”) has been suggested as a possible method for estimating postmortem interval (PMI) for forensic analyses. Here we evaluate human gut bacterial populations to determine quantifiable, time‐dependent changes postmortem. Gut microflora were repeatedly sampled from the proximal large intestine of 12 deceased human individuals as they decayed under environmental conditions. Three intestinal bacterial genera were quantified by quantitative PCR (qPCR) using group‐specific primers targeting 16S rRNA genes. Bacteroides and Lactobacillus relative abundances declined exponentially with increasing PMI at rates of N_t = 0.977e^?0.0144t (r² = 0.537, p < 0.001) and N_t = 0.019e^?0.0087t (r² = 0.396, p < 0.001), respectively, where N_t is relative abundance at time (t) in cumulative degree hours. Bifidobacterium relative abundances did not change significantly: N_t = 0.003e^?0.002t (r² = 0.033, p = 0.284). Therefore, Bacteroides and Lactobacillus abundances could be used as quantitative indicators of PMI.     

A Test of Sex Estimation in Subadults Using the Elevation of the Auricular Surface from Four Samples of Known Age and Sex

Biological sex is foundational to the work of forensic anthropologists and bioarcheologists. The lack of reliable biological sex estimation methods for subadults has, thus, greatly limited forensic and bioarcheological analyses. Auricular surface elevation showed promise as a subadult sex estimation method in previous studies. This study examined two auricular surface elevation evaluation methods on four subadult samples of known age, sex, and ancestry. Samples were scored as “male,” “female,” or “indeterminate” and results were examined with chi‐square analysis. No consistent sex estimation pattern, accuracy, or predictive value was produced between samples. Only one test was significant using Fisher's exact test analysis (FET = 7.501, p < 0.022): the composite approach on the Hamann‐Todd sample. While age, sample size, or developmental factors may play a role in these results, clearly sample variation does as well. This study found auricular surface elevation was not a useful subadult sex estimation method.     

Morphoscopic Trait Expression in “Hispanic” Populations

This study evaluates population variation of eight cranial morphoscopic traits using samples of known southwest Hispanics (n = 72), Guatemalans (n = 106), American Blacks (n = 146), and American Whites (n = 218). We applied the support vector machine (SVM) method to build a prediction model based on a subsample (20%) of the data; the remainder of the data was used as a test sample. The SVM approach effectively differentiated between the four groups with correct classification rates between 72% (Guatemalan group) and 94% (American Black group). However, when the Guatemalan and southwest Hispanic samples were pooled, the same model correctly classified all groups with a higher degree of accuracy (American Black = 96%; American White = 77%; and the pooled Hispanic sample = 91%). This study also identified significant differences between the two Hispanic groups in six of the eight traits using univariate statistical tests. These results speak to the unique population histories of these samples and the current use of the term “Hispanic” within forensic anthropology. Finally, we argue that the SVM can be used as a classification model for ancestry estimation in a forensic context and as a diagnostic tool may broaden the application of morphoscopic trait data for the assessment of ancestry.     

Development of the supernormality scale-revised and its relationship with psychopathy

Abstract:  The current research addresses the psychometric and diagnostic qualities of the Supernormality Scale-Revised (SS-R), a self-report measurement. Supernormality is defined as the tendency to systematically deny the presence of common symptoms (e.g., intrusive thoughts). In study 1, the SS-R was administered to forensic patients ( n  = 63), psychiatric patients ( n  = 26), honestly responding students ( n  = 26), and students instructed to fake supernormality ( n  = 20). Findings indicated good test–retest stability, and adequate internal consistency. Furthermore, the SS-R showed overall good predictive and convergent validity. Moreover, the diagnostic accuracy was excellent (sensitivity and specificity being 0.80 and 0.92, respectively). In study 2, 115 (healthy) controls and 32 forensic patients completed the SS-R and the Psychopathic Personality Inventory (PPI) ( J Pers Assess 1996; 66 :488), an instrument measuring psychopathy. Results showed again that the SS-R is a reliable and valid instrument. However, supernormality was not related to psychopathy as measured by the PPI.     

Testing a Novel 3D Printed Radiographic Imaging Device for Use in Forensic Odontology

There are specific challenges related to forensic dental radiology and difficulties in aligning X‐ray equipment to teeth of interest. Researchers used 3D printing to create a new device, the combined holding and aiming device (CHAD), to address the positioning limitations of current dental X‐ray devices. Participants (N = 24) used the CHAD, soft dental wax, and a modified external aiming device (MEAD) to determine device preference, radiographer's efficiency, and technique errors. Each participant exposed six X‐rays per device for a total of 432 X‐rays scored. A significant difference was found at the 0.05 level between the three devices (p = 0.0015), with the MEAD having the least amount of total errors and soft dental wax taking the least amount of time. Total errors were highest when participants used soft dental wax—both the MEAD and the CHAD performed best overall. Further research in forensic dental radiology and use of holding devices is needed.     

Determination of Sex: Interest of Frontal Sinus 3D Reconstructions

Frontal sinuses (FSs) have been studied in radiology, anthropology, and forensic anthropology. This study aimed to determine whether it was possible to predict the age and sex of an individual using FS volume. Sixty‐nine anonymized CT scans were imported to MIMICS 10.01^® software (Materialise N.V.), and each FS volume was calculated in mm³. There was an absence of significant difference between right and left FS volume (p = 0.173) and an absence of correlation between age and FS volume (Pearson's test; p = 0.705). Sexual dimorphism was significantly different (p = 0.001). However, the most discriminant datum for determining sex was found to be the total FS volume (sum of an individual's right and left FS volumes) with linear discriminant Fisher's function coefficients of ?2.759 for the male group and ?1.275 for the female group. With this model, 72.5% of our sample was correctly classified according to sex.     

Diagnosing Crime and Diagnosing Disease: Bias Reduction Strategies in the Forensic and Clinical Sciences

Cognitive effort is an essential part of both forensic and clinical decision‐making. Errors occur in both fields because the cognitive process is complex and prone to bias. We performed a selective review of full‐text English language literature on cognitive bias leading to diagnostic and forensic errors. Earlier work (1970–2000) concentrated on classifying and raising bias awareness. Recently (2000–2016), the emphasis has shifted toward strategies for “debiasing.” While the forensic sciences have focused on the control of misleading contextual cues, clinical debiasing efforts have relied on checklists and hypothetical scenarios. No single generally applicable and effective bias reduction strategy has emerged so far. Generalized attempts at bias elimination have not been particularly successful. It is time to shift focus to the study of errors within specific domains, and how to best communicate uncertainty in order to improve decision making on the part of both the expert and the trier‐of‐fact.     

Spread and habitat selection of Chrysomya albiceps (Wiedemann) (Diptera Calliphoridae) in Northern Italy: forensic implications

Abstract: Habitat selection exploited by Chrysomya albiceps during its initial spread in Northern Italy was analyzed in relation to landscape structure. The results of two short studies and a case report are here discussed. C. albiceps was not found on experimental pig carcasses in the urban area of Pavia. It was missing in the woody mountains surrounding Lecco, but it was found in the same area, at a lower altitude, within the typical “urban sprawl” landscape. It was then recorded in a natural reserve, among a rich carrion‐fly population. Indications coming from habitat selection suggest that C. albiceps has not yet saturated its potential ecological niche in newly colonized areas of Northern Italy. Factors like temperature, altitude, and interspecific competition can act as limiting factors, affecting habitat selection and distribution in newly colonized areas; the influence of those factors has to be taken into account for forensic purposes.     

National Academy of Sciences “Standardization”: On What Terms?

The frequently cited 2009 National Academy of Sciences Report entitled “Strengthening Forensic Science in the United States: A Path Forward” has become a focal point of forensic science practitioners' discussions and research since its publication. One of its recommendations is “Standardized Terminology and Reporting”. Little has been published to date on this topic, although conversations and dialogs on the subject are ongoing. The upshot of this communication is to draw attention to the problem of one term in particular, perimortem, which may be only the proverbial “tip of the iceberg” in the lexicon‐related concerns of forensic scientists. Even if it is an isolated issue, it is one that reflects the need for a consensus on term use and definitions by interdisciplinary practitioners who are currently using the term haphazardly, to the confusion of colleagues and potentially finders‐of‐fact in the courts.     

A Proposed Scheme for Classifying Pediatric Rib Head Fractures Using Case Examples

Pediatric rib head fractures are typically described as “posterior” or “costovertebral,” terms lacking specificity. To resolve this issue, a scheme was developed to describe the location of rib head fractures observed in a pediatric forensic population. The scheme uses three anatomical landmarks, terminus (tip), tubercle, and costovertebral articular surface to divide the rib head into two subregions, costovertebral and costotransverse. Examples of five cases of infants with rib head fractures are presented using this scheme. Forty‐eight rib head fractures were observed in these infants with the following frequencies: 56% (three infants) at the terminus; 21% (three infants) in the costovertebral subregion; 21% (one infant) at the costovertebral articular facet; and 2% (one infant) in the costotransverse subregion. Due to the small number of cases assessed, statistical analyses could not be performed; however, the data demonstrate the variation in distribution of pediatric rib head fractures.     

Geophysical Monitoring of Simulated Clandestine Graves Using Electrical and Ground‐Penetrating Radar Methods: 0–3 Years After Burial*,†

Abstract: This study provides forensic search teams with systematic geophysical monitoring data over simulated clandestine graves for comparison to active cases. Simulated “wrapped” and “naked” burials were created. Multigeophysical surveys were collected over a 3‐year monitoring period. Bulk ground resistivity, electrical resistivity imaging, multifrequency ground‐penetrating radar (GPR), and grave and background “soil‐water” conductivity data were collected. Resistivity surveys revealed the naked burial had consistently low‐resistivity anomalies, whereas the wrapped burial had small, varying high‐resistivity anomalies. GPR 110‐ to 900‐MHz frequency surveys showed the wrapped burial could be detected throughout, with the “naked” burial mostly resolved. Two hundred and twenty‐five megahertz frequency GPR data were optimal. “Soil‐water” analyses showed rapidly increasing (year 1), slowly increasing (year 2), and decreasing (year 3) conductivity values. Results suggest resistivity and GPR surveys should be collected if target “wrapping” is unknown, with winter to spring surveys optimal. Resistivity surveys should be collected in clay‐rich soils.     

Comparison Among Manual Facial Approximations Conducted by Two Methodological Approaches of Face Prediction

This study verified the difference between two methods of forensic facial approximation (FFA) regarding recognition and resemblance rates. Three‐dimensional models of skulls were obtained from computerized tomography (CT) scans of two subjects (targets). Two manual FFAs were performed for each target, by applying two different guidelines for the facial structures (what we called “American method” (AM) and “Combined method” (CM)). Unfamiliar assessors evaluated the sculptures by recognition and resemblance tests. The AM was that which allowed more correct responses of recognition and higher resemblance's scores for the male target (p < 0.001). Regarding guidelines for modeling characteristics of the face, the ones that are practical and easily performed for sculptures, such as the length of the anterior nasal spine multiplied by 3 for nose prediction, may offer better results in terms of resemblance.     

Estimating the preappearance interval from temperature in Creophilus maxillosus L. (Coleoptera: Staphylinidae)

Abstract: Some carrion insects appear on carcasses late in decomposition. While using these late‐arriving taxa to estimate postmortem interval, it is vital to accurately estimate an interval preceding their appearance on a cadaver called the preappearance interval (PAI). This paper tests the possibilities of a PAI estimation from temperature in case of late‐arriving, predatory carrion beetle Creophilus maxillosus. The relationship between temperature and PAI of adult and larval C. maxillosus was modeled using the results of a large‐scale experiment on succession in forests of Central Europe. In both stages, PAI was found to be strongly, inversely related to temperature averaged for the duration of PAI. The PAI estimation from mean degree‐day accumulations (mDDA), estimated DDA, and “PAI*T” functions were tested using external successional data. The greatest accuracy of PAI estimates was achieved using an exponential “PAI*T” function.     

Ruptured Syphilitic Aneurysm: A Cause of Sudden Death in a Man with Human Immunodeficiency Coinfection

Syphilis, a sexually transmitted infection caused by the bacterium Treponema palladium, is experiencing a worldwide resurgence. The risk of syphilis infection is particularly high in men who have sex with men (MSM), especially those who are human immunodeficiency virus (HIV)‐positive. Untreated syphilis can lead to rare but severe late‐stage complications, including syphilitic aortitis. Herein, we present an autopsy case of a ruptured thoracic aneurysm that resulted from an undetected case of syphilitic aortitis in an HIV‐positive Japanese MSM with undiagnosed syphilis. Although no syphilitic skin lesions were observed on the body, anatomical changes consistent with a syphilitic etiology were present at the site of the rupture, including medial aortic scarring with “tree‐bark”‐like atherosclerotic plaque. In addition, heart blood was positive for T. palladium in a latex agglutination test. This case highlights for forensic pathologists the importance of recognizing syphilis as a possible underlying cause of sudden death among HIV‐positive MSM.     

Error Rates,Likelihood Ratios,and Jury Evaluation of Forensic Evidence

Forensic examiners regularly testify in criminal cases, informing the jurors whether crime scene evidence likely came from a source. In this study, we examine the impact of providing jurors with testimony further qualified by error rates and likelihood ratios, for expert testimony concerning two forensic disciplines: commonly used fingerprint comparison evidence and a novel technique involving voice comparison. Our method involved surveying mock jurors in Amazon Mechanical Turk (N = 897 laypeople) using written testimony and judicial instructions. Participants were more skeptical of voice analysis and generated fewer “guilty” decisions than for fingerprint analysis (B = 2.00, OR = 7.06, p = <0.000). We found that error rate information most strongly decreased “guilty” votes relative to no qualifying information for participants who heard fingerprint evidence (but not those that heard voice analysis evidence; B = −1.16, OR = 0.32, p = 0.007). We also found that error rates and conclusion types led to a greater decrease on “guilty” votes for fingerprint evidence than voice evidence (B = 1.44, OR = 4.23, p = 0.021). We conclude that these results suggest jurors adjust the weight placed on forensic evidence depending on their prior views about its reliability. Future research should develop testimony and judicial instructions that can better inform jurors of the strengths and limitations of forensic evidence.     

“YFlag” – A Single‐base Extension Primer Based Method for Gender Determination

Assigning the gender of a DNA contributor in forensic analysis is typically achieved using the amelogenin test. Occasionally, this test produces false‐positive results due to deletions occurring on the Y chromosome. Here, a four‐marker “YFlag” method is presented to infer gender using single‐base extension primers to flag the presence (or absence) of Y‐chromosome DNA within a sample to supplement forensic STR profiling. This method offers built‐in redundancy, with a single marker being sufficient to detect the presence of male DNA. In a study using 30 male and 30 female individuals, detection of male DNA was achieved with c. 0.03 ng of male DNA. All four markers were present in male/female mixture samples despite the presence of excessive female DNA. In summary, the YFlag system offers a method that is reproducible, specific, and sensitive, making it suitable for forensic use to detect male DNA.     

Fatal Overdose of Gamma‐hydroxybutyrate Acid After Ingestion of 1,4‐Butanediol

We report a case of fatal intoxication from 1,4‐butanediol (1,4‐BD), which was ingested by a young and “naïve” gamma‐hydroxybutyrate (GHB) consumer during a party with the co‐ingestion of alcohol, cannabis, and methylene‐dioxy‐methamphetamine. The following drug concentrations were found using gas chromatography coupled with mass spectrometry on autopsy samples and on a cup and a glass found at the scene: 20,350 mg/L (bottle) for 1,4‐BD; 1020 mg/L (femoral blood), 3380 mg/L (cardiac blood), 47,280 mg/L (gastric content), and 570 mg/L (vitreous humor) for GHB. The concentration of GHB is difficult to interpret in forensic cases due to the possibility of an endogenous production of GHB. The variable tolerance of the user may also modify the peri‐ and postmortem GHB concentrations. This case underscores the need to have many different sources of toxicology samples analyzed to avoid the hypothesis of endogenous production of GHB.     

Meeting a Forensic Podiatry Admissibility Challenge: A Daubert Case Study

This article is an introduction to the United States Supreme Court's standard of admissibility of forensic evidence and testimony at trial, known as the Daubert standard, with emphasis on how this standard applies to the field of forensic podiatry. The author, a forensic podiatrist, provided law enforcement with evidence tying a bloody sock‐clad footprint found at the scene of a homicide to the suspect. In 2014, the author testified at a pretrial hearing, known as “a Daubert hearing,” to address the admissibility of this evidence in court. This was the first instance of forensic podiatry being the primary subject of a Daubert hearing. The hearing resulted in the court ordering this evidence admissible. The expert's testimony contributed to the suspect's conviction. This article serves as a reference for forensic podiatrists and experts in similar fields that involve impression evidence, providing evidentiary standards and their impact on expert evidence and testimony.     

The Optimized Summed Scored Attributes Method for the Classification of U.S. Blacks and Whites: A Validation Study

Recently, Hefner and Ousley (2014) introduced the optimized summed scored attributes (OSSA) method that maximizes between‐group differences in U.S. black and white populations by dichotomizing six cranial morphoscopic trait scores. This study tests OSSA using an independent skeletal sample (Hamann‐Todd, n = 208) and positively identified forensic cases (Mercyhurst University, n = 28, and New York City Office of Chief Medical Examiner, n = 38). An evaluation of trait frequencies suggests shifting the heuristically selected sectioning point separating U.S. black and white populations from ≤ 3 to ≤ 4. We found a total correct classification of 73.0% (B = 50.9%, W = 89.2%) using the originally suggested sectioning point of ≤3, while the total correct classification increases to 79.2% (B = 80.2%, W = 78.5%) with a modified sectioning point of ≤4. With the increased total correct classification and reduced classification bias between ancestry groups, we suggest the modified sectioning point of ≤4 be used when assessing ancestry in forensic unknowns.     

Bone Mineral Density Adult Age Estimation in Forensic Anthropology: A Test of the DXAGE Application

Estimating age‐at‐death of individuals represented only by skeletonized human remains is a fundamental aspect of forensic anthropological casework. Recently, several researchers have proposed that bone mineral density (BMD) is a useful predictor of age‐at‐death in forensic contexts. Navega et al. (JFS 63(2):497–503) developed an online application called DXAGE for calculating age‐at‐death from BMD parameters. This study tests the utility of DXAGE by utilizing data from the National Health and Nutrition Examination Survey (NHANES). BMD data from a female subsample (n = 470) of the NHANES 2007–2008 dataset were analyzed, and the relationship between predicted age and real age was examined. Inaccuracy was 14.25 years, and bias was ?7.20 years. Results show that there is a weak correlation between predicted and actual age (r = 0.47) using the DXAGE application. While BMD data are potentially useful for predicting age age‐at‐death, the DXAGE application should be used cautiously in forensic anthropological contexts.