Age‐Dependent Fracture Characteristics of Rigid and Compliant Surface Impacts on the Infant Skull—A Porcine Model*,†

Abstract: This study documents skull fracture characteristics on infant porcine specimens under known impact conditions with respect to age and interface. A single impact causing fracture was conducted on the skull of porcine specimens aged 2–28 days (n = 76). Paired rigid and compliant impacts at the same energy were conducted at each specimen age. Impact force, impact duration, and fracture length were recorded. Energy required to initiate skull fracture increased with specimen age. For a given energy, impact of the skull with a compliant interface caused more fracture damage than with a rigid interface for specimens aged under 17 days, but less damage for specimens aged 24–28 days. The documentation of energy required to cause fracture and resulting fracture propagation with respect to impact interface and age may be of critical importance in forensic investigations of infant skull trauma.     

The Accuracy and Applicability of 3D Modeling and Printing Blunt Force Cranial Injuries

The purpose of this study was to determine the factors affecting the accuracy of 3D models and 3D prints of cranial blunt force trauma, to evaluate the applicability and limitations of modeling such injuries. Three types of cranial blunt force lesions were documented (hinge, depressed, and comminuted) using three forms of surface scanning (laser, structured light scanner, and photogrammetry) at two different quality settings (standard and high). 3D printed models of the lesions were produced using two different materials (a gypsum‐like composite powder called VisiJet^® PXL and an acrylic engineered composite plastic called VisiJet^® M3 in crystal colour). The results of these analyzes indicate the prints in this study exhibit some statistically significant differences from the actual bone lesions, but details of the lesions can be reproduced to within 2 mm accuracy.     

The Validity of Ear Prediction Guidelines Used in Facial Approximation*,†,‡

Abstract: This study examined eight previously published ear prediction methods by Welcker, Gerasimov, Fedosyutkin and Nainys, and Broadbent and Mathews. Computed tomography scans of 78 living adults (n₁) did not support any of these previously published recommendations. Free earlobes were found to accompany protruding supramastoid crests (Pearson’s χ² < 0.05); and ear length [l] and width [w] differed by sex (p < 0.05), correlated with age (r = 0.38[l]; 0.32[w]), and correlated with facial height (r = 0.37[l]; 0.30[w]). New regression equations (for ear length and width) were generated using these variables in several samples and, where possible, cross‐validated using independent data (n₁ = 78, n₂ = 2190, n₃ = 1328, n₄ = 1010, and n₅ = 47). As a result of these analyses, four valid and tested methods for ear prediction were identified, but large degrees of error continue to make accurate prediction of the ear, from the skull, problematic.     

The Role of Interface on the Impact Characteristics and Cranial Fracture Patterns Using the Immature Porcine Head Model

The role of impact interface characteristics on the biomechanics and patterns of cranial fracture has not been investigated in detail, and especially for the pediatric head. In this study, infant porcine skulls aged 2–19 days were dropped with an energy to cause fracturing onto four surfaces varying in stiffness from a rigid plate to one covered with plush carpeting. Results showed that heads dropped onto the rigid surface produced more extensive cranial fracturing than onto carpeted surfaces. Contact forces generated at fracture initiation and the overall maximum contact forces were generally lower for the rigid than carpeted impacts. While the degree of cranial fracturing from impacts onto the heavy carpeted surface was comparable to that of lower‐energy rigid surface impacts, there were fewer diastatic fractures. This suggests that characteristics of the cranial fracture patterns may be used to differentiate energy level from impact interface in pediatric forensic cases.     

Classification of Porcine Cranial Fracture Patterns Using a Fracture Printing Interface,,

Distinguishing between accidental and abusive head trauma in children can be difficult, as there is a lack of baseline data for pediatric cranial fracture patterns. A porcine head model has recently been developed and utilized in a series of studies to investigate the effects of impact energy level, surface type, and constraint condition on cranial fracture patterns. In the current study, an automated pattern recognition method, or a fracture printing interface (FPI), was developed to classify cranial fracture patterns that were associated with different impact scenarios documented in previous experiments. The FPI accurately predicted the energy level when the impact surface type was rigid. Additionally, the FPI was exceedingly successful in determining fractures caused by skulls being dropped with a high‐level energy (97% accuracy). The FPI, currently developed on the porcine data, may in the future be transformed to the task of cranial fracture pattern classification for human infant skulls.     

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.     

Evaluation of Stature Estimation from the Database for Forensic Anthropology*†

Abstract: Trotter and Gleser’s ( 1 - 3 ) stature equations, conventionally used to estimate stature, are not appropriate to use in the modern forensic context. In this study, stature is assessed with a modern (birth years after 1944) American sample (N = 242) derived from the National Institute of Justice Database for Forensic Anthropology in the United States and the Forensic Anthropology Databank. New stature formulae have been calculated using forensic stature (FSTAT) and a combined dataset of forensic, cadaver, and measured statures referred to as Any Stature (ASTAT). The new FSTAT‐based equations had an improved accuracy in Blacks with little improvement over Ousley’s ( 4 ) equations for Whites. ASTAT‐based equations performed equal to those of FSTAT equations and may be more appropriate, because they reflect both the variation in reported statures and in cadaver statures. It is essential to use not only equations based on forensic statures, but also equations based on modern samples.     

The Role of Interface Shape on the Impact Characteristics and Cranial Fracture Patterns Using the Immature Porcine Head Model, ,

The forensic literature suggests that when adolescents fall onto edged and pointed surfaces, depressed fractures can occur at low energy levels. This study documents impact biomechanics and fracture characteristics of infant porcine skulls dropped onto flat, curved, edged, and focal surfaces. Results showed that the energy needed for fracture initiation was nearly four times higher against a flat surface than against the other surfaces. While characteristic measures of fracture such as number and length of fractures did not vary with impact surface shape, the fracture patterns did depend on impact surface shape. While experimental impacts against the flat surface produced linear fractures initiating at sutural boundaries peripheral to the point of impact (POI), more focal impacts produced depressed fractures initiating at the POI. The study supported case‐based forensic literature suggesting cranial fracture patterns depend on impact surface shape and that fracture initiation energy is lower for more focal impacts.     

Pilot Study of Automated Bullet Signature Identification Based on Topography Measurements and Correlations*†

Abstract: A procedure for automated bullet signature identification is described based on topography measurements using confocal microscopy and correlation calculation. Automated search and retrieval systems are widely used for comparison of firearms evidence. In this study, 48 bullets fired from six different barrel manufacturers are classified into different groups based on the width class characteristic for each land engraved area of the bullets. Then the cross‐correlation function is applied both for automatic selection of the effective correlation area, and for the extraction of a 2D bullet profile signature. Based on the cross‐correlation maximum values, a list of top ranking candidates against a ballistics signature database of bullets fired from the same model firearm is developed. The correlation results show a 9.3% higher accuracy rate compared with a currently used commercial system based on optical reflection. This suggests that correlation results can be improved using the sequence of methods described here.     

Automated Mapping of Explosives Particles in Composition C‐4 Fingerprints*†‡

Abstract: A method is described to perform automated mapping of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) particles in C‐4 fingerprints. The method employs polarized light microscopy and image analysis to map the entire fingerprint and the distribution of RDX particles. This method can be used to evaluate a large number of fingerprints to aid in the development of threat libraries that can be used to determine performance requirements of explosive trace detectors. A series of 50 C‐4 fingerprints were characterized, and results show that the number of particles varies significantly from print to print, and within a print. The particle size distributions can be used to estimate the mass of RDX in the fingerprint. These estimates were found to be within ±26% relative of the results obtained from dissolution gas chromatography/μ‐electron capture detection for four of six prints, which is quite encouraging for a particle counting approach. By evaluating the average mass and frequency of particles with respect to size for this series of fingerprints, we conclude that particles 10–20 μm in diameter could be targeted to improve detection of traces of C‐4 explosives.     

Assessment of Wear‐Related Features of the Kerf Wall from Saw Marks in Bone*†

Abstract: Analyses of saw marks in bone may yield important information about the class characteristics of saws used in postmortem dismemberments, yet little research has been directed at identifying saws’ individualizing characteristics. This study adds to existing saw mark analysis methodologies by examining wear‐related features of kerf walls using light‐ and environmental scanning electron microscopy. A crosscut saw and hacksaw were used to create sequences of 30 cuts in bone; these sequences reveal patterns of progressive loss of fine details of kerf wall morphology with increasing saw blade wear, because of the rounding of sharp points and edges. Nevertheless, diagnostic kerf wall features used to establish class characteristics persist despite these wear‐related changes. Unsuccessful attempts at statistical analysis of wear‐related changes, based on striae width and density, suggest these patterns are not readily quantifiable. Additionally, despite the scanning electron microscope’s superior imaging capabilities, it provided few practical, methodological gains over traditional light microscopy.     

Positive “Water Test”—An External Indicator of Base of Skull Hinge‐Ring Fracture

Abstract: Despite having significant internal injuries, victims of motor vehicle accidents may have surprisingly few external manifestations of trauma. The water test describes a technique whereby water placed in an upwardly facing ear results in drainage from the nose and opposite ear, thus demonstrating transcranial passage of water. This sign can be demonstrated in cases of blunt cranial trauma where there is a “hinge” fracture involving the petrous temporal bones bilaterally associated with a ring fracture extending around the foramen magnum posteriorly. Such a fracture results in separation of the posterior and middle cranial fossae providing a track for water to traverse. The water test provides a quick and noninvasive method for demonstrating the presence of a particular type of skull fracture.     

Development of a Nomenclature System for a Canine STR Multiplex Reagent Kit*†

Abstract: Despite the popularity of dogs in US households, canine DNA evidence remains largely untapped in forensic investigations partially because of the absence of well‐defined forensic short tandem repeats (STRs), lack of standardized and validated PCR protocols, STR reagent kits, and poorly developed nomenclature. A nomenclature system was established based on internationally recognized recommendations for human forensic STRs for a recently developed canine STR reagent kit. Representative alleles were sequenced from each of the 18 STRs and the sex‐typing marker included in the kit. This study also reflects on the impact of point mutations, insertions, and deletions within and outside the STR core repeat structures. An understanding of the STRs’ sequence and repeat structures will enable development of a robust and reliable allele nomenclature and improve the accuracy and precision of allele fragment sizing in canine forensic profiling. The expected allele sizes have been calculated, and their repeat stuctures defined based on sequence information.     

Computational Study of Fracture Characteristics in Infant Skulls Using a Simplified Finite Element Model

Skull fracture characteristics are associated with loading conditions (such as the impact point and impact velocity) and could provide indication of abuse or accident‐induced head injuries. However, correlations between fracture characteristics and loading conditions in infant and toddler are ill‐understood. A simplified computational model representing an infant head was built to simulate skull responses to blunt impacts. The fractures were decided through a first principal strain‐based element elimination strategy. Simulation results were qualitatively compared with test data from porcine heads. This simplified model well captured the fracture pattern, initial fracture position, and direction of fracture propagation. The model also very well described fracture characteristics found in studies with human infant cadaveric specimens. A series of parametric studies was conducted, and results indicated that the parameters studied had substantial effects on fracture patterns. Additionally, the jagged shapes of sutures were associated with strain concentrations in the skull.     

Heteroplasmy in Hair: Study of Mitochondrial DNA Third Hypervariable Region in Hair and Blood Samples*†

Abstract: Mitochondrial DNA (mtDNA) analysis has proved useful for forensic identification especially in cases where nuclear DNA is not available, such as with hair evidence. Heteroplasmy, the presence of more than one type of mtDNA in one individual, is a common situation often reported in the first and second mtDNA hypervariable regions (HV1/HV2), particularly in hair samples. However, there is no data about heteroplasmy frequency in the third mtDNA hypervariable region (HV3). To investigate possible heteroplasmy hotspots, HV3 from hair and blood samples of 100 individuals were sequenced and compared. No point heteroplasmy was observed, but length heteroplasmy was, both in C‐stretch and CA repeat. To observe which CA “alleles” were present in each tissue, PCR products were cloned and re‐sequenced. However, no variation among CA alleles was observed. Regarding forensic practice, we conclude that point heteroplasmy in HV3 is not as frequent as in the HV1/HV2.     

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.     

The Analysis of Black Powder Substitutes Containing Ascorbic Acid by Ion Chromatography/Mass Spectrometry*†

Abstract: Black powder substitutes containing ascorbic acid are a group of low explosives that utilize ascorbic acid as the fuel. The analysis of these powders is complicated by the degradation of ascorbic acid which occurs rapidly in solution and may also occur as the powder ages. Aqueous extracts of both intact powders and postblast residues were analyzed by an existing ion chromatography/mass spectrometry (IC/MS) method used at the Bureau of Alcohol, Tobacco, Firearms and Explosives. Results have shown that while ascorbic acid itself is not detected in this method, its diagnostic degradation products (threonic acid, monohydrated diketogulonic acid, and oxalic acid) can be identified. In addition, anions from the inorganic oxidizers (perchlorate and nitrate) and combustion products such as chloride, chlorate, and nitrite, can be identified within the same experiment. While this IC/MS method shows promise, future modifications are necessary because of limitations in identifying threonate in postblast residues, as well as coeluting compounds observed in postblast residues.     

Forensic Discrimination of Dyed Hair Color: I. UV‐Visible Microspectrophotometry*†

Abstract: Current protocols for examining hair do not attempt to differentiate hair color using instrumental analysis. In this study, hair samples treated with 55 different red hair dyes were analyzed using UV‐visible microspectrophotometry between 200 and 700 nm. Using air as a background reference gave the best results, although mounting media such as glycerin could also be used. The contribution of the hair substrate is predominantly observed in the range of 300–400 nm while the dye peak is evident in the range of 425–550 nm. It was found that the presence of hair dye reduces the overall intrasample variability of the hair color. In addition, visual inspection and spectral interpretation showed that dyed hair exhibits distinct and discernable shades. The color of all samples was stable during storage and while all hair dyes fade with washing, significant fading of the color was only evident after daily washing for 3 weeks.     

Fatal Firearm Injuries in Tennessee: A Comparison Study of Tennessee's Two Most Populous Counties 2009–2012

Firearm injuries are a leading cause of violent death in Tennessee. This study was designed to compare the demographic and epidemiologic features of fatal firearm injuries in Shelby County and Davidson County, Tennessee between 2009 and 2012. We identified 1081 gunshot fatalities for the study period in these two counties. Shelby County had a higher overall, age‐adjusted gunshot mortality rate, a higher male age‐adjusted gunshot mortality rate, and a higher age‐adjusted gunshot homicide rate than Davidson. Age groups 25–34 years and 35–44 years had higher crude mortality rates for gunshot deaths in Shelby County than Davidson County. Both counties had higher age‐adjusted gunshot mortality rates for black males than white males, higher homicide rate for black race than white, and higher suicide rate for white race than black. Homicide was the most common manner of death, and handguns were the most common type of firearm used in both counties.     

Forensic Approach to an Archaeological Casework of “Vampire” Skeletal Remains in Venice: Odontological and Anthropological Prospectus*

Abstract: During the years 2006–2007, the Archeological Superintendent of Veneto (Italy) promoted a research project on mass graves located on Nuovo Lazzaretto in Venice, where the corpses of plague deaths were buried during the 16th and 17th centuries. The burials were of different stages and are believed to be the remains of plague victims from the numerous outbreaks of pestilence, which occurred between the 15th and 17th centuries. Among the fragmented and commingled human bones, an unusual burial was found. The body was laid supine, with the top half of the thorax intact, arms parallel to the rachis axis, the articulations were anatomically unaltered. Both the skull morphology and the dimensions of the caput omeris suggest the body was a woman. A brick of moderate size was found inside the oral cavity, keeping the mandible wide open. The data collected by the anthropologist were used to generate a taphonomic profile, which precluded the positioning of the brick being accidental. Likewise, the probability of the brick having come from the surrounding burial sediment was rejected, as the only other inclusions found were bone fragments from previous burials in the same area. The data collected by the odontologist were employed for age estimation and radiological dental assessment. The forensic profile was based conceptually on the “circumstances of death” and concluded that the positioning of the brick was intentional, and attributed to a symbolic burial ritual. This ritual confirms the intimate belief held at those times, between the plague and the mythological character of the vampire.