Scanning electron microscopy (SEM) has occasionally been used by anthropologists and forensic scientists to look at morphological characteristics that certain implements leave on bone. However, few studies have addressed techniques or protocols for assessing quantitative differences between tool marks on bone made by different bladed implements. In this study, the statistical variation in cut mark width was examined between control and test samples on bone using a scalpel blade, paring knife, and kitchen utility knife. Statistically significant differences (p < .0005) were found between cut marks made by the same knife under control and test conditions for all three knife types used in the study. When the control sample and test samples were examined individually for differences in mean variation between knife types, significant differences were also found (p < .0005). While significant differences in cut mark width were found, caution should be used in trying to classify individual cut marks as being inflicted by a particular implement, due to the overlap in cut mark width that exists between different knife types. When combined, both quantitative and qualitative analyses of cut marks should prove to be more useful in trying to identify a suspect weapon. Furthermore, the application of SEM can be particularly useful for assessing many of these features.

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Microscopic saw mark analysis is a well published and generally accepted qualitative analytical method. However, little research has focused on identifying and mitigating potential sources of error associated with the method. The presented study proposes the use of classification trees and random forest classifiers as an optimal, statistically sound approach to mitigate the potential for error of variability and outcome error in microscopic saw mark analysis. The statistical model was applied to 58 experimental saw marks created with four types of saws. The saw marks were made in fresh human femurs obtained through anatomical gift and were analyzed using a Keyence digital microscope. The statistical approach weighed the variables based on discriminatory value and produced decision trees with an associated outcome error rate of 8.62-17.82%.

Rib fractures are considered highly suspicious for nonaccidental injury in the pediatric clinical literature; however, a rib fracture classification system has not been developed. As an aid and impetus for rib fracture research, we developed a concise schema for classifying rib fracture types and fracture location that is applicable to infants. The system defined four fracture types (sternal end, buckle, transverse, and oblique) and four regions of the rib (posterior, posterolateral, anterolateral, and anterior). It was applied to all rib fractures observed during 85 consecutive infant autopsies. Rib fractures were found in 24 (28%) of the cases. A total of 158 rib fractures were identified. The proposed schema was adequate to classify 153 (97%) of the observed fractures. The results indicate that the classification system is sufficiently robust to classify rib fractures typically observed in infants and should be used by researchers investigating infant rib fractures.

This study was designed to establish the potential error rate associated with the generally accepted method of tool mark analysis of cut marks in costal cartilage. Three knives with different blade types were used to make experimental cut marks in costal cartilage of pigs. Each cut surface was cast, and each cast was examined by three analysts working independently. The presence of striations, regularity of striations, and presence of a primary and secondary striation pattern were recorded for each cast. The distance between each striation was measured. The results showed that striations were not consistently impressed on the cut surface by the blade's cutting edge. Also, blade type classification by the presence or absence of striations led to a 65% misclassification rate. Use of the classification tree and cross-validation methods and inclusion of the mean interstriation distance decreased the error rate to c. 50%.

In 2012, the Harris County Institute of Forensic Sciences began prospectively collecting injury data from pediatric autopsies. These data and associated case information from 635 pediatric cases are archived in the Infant Injury Database (IID). This paper introduces the IID to the forensic community and demonstrates its potential utility for child abuse and infant fatality investigations. The database is intended to be a source of evidence‐based research for coroners/medical examiners and clinicians in the recognition and diagnosis of child abuse. RR estimates were employed to quantify the relationship between individual autopsy findings to trauma‐related and nontrauma‐related causes of death. For example, unsurprisingly, the RR of trauma cases with multiple injury types is significantly greater than other causes of death, but the RR results provide a quantitative representation of the relationship. ROC curve modeling of the presence/absence of various injury types performed well at discriminating trauma from other causes of death (AUC = 0.96).

The pediatric skeletal examination (PSE) is an autopsy technique recommended for pediatric cases suspicious for nonaccidental injury. The technique requires the reflection of the musculature and periosteum of the ribs, clavicles, long bones, and scapulae, and inspection of the bone surfaces and chondro-osseous interfaces. The technique is time consuming, labor intensive and possibly disfiguring. Therefore, the value of the technique must be measured against the cost. The present study was designed to evaluate the impact of the PSE on the sensitivity of the autopsy. A non-randomized retrospective review of 94 autopsy reports was done. The cause and manner of death for each case was classified as blunt force trauma and homicide. Half of the sample received a PSE during the autopsy and half did not. The number of rib and long bone fractures noted in the reports was significantly greater in the group that received the PSE. The number of cranial, scapular and clavicular fractures was not significantly different between the two groups. The PSE does not increase the visibility of the neurocranium; therefore, a difference in the number of cranial fractures was not expected. Scapular and clavicular fractures were rare in the study population. The insignificant difference between the two groups may be a reflection of the rarity of the fracture as opposed to the sensitivity of the PSE. The results of the study indicate that the PSE increases the sensitivity of the pediatric autopsy with respect to long bone and rib fractures.

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.