Indoor Wet Screening of Exhumed Skeletal Remains: A Suggested Procedure for the Preparation of Fragile Evidence for Anthropological Analysis

Abstract: The 2007 exhumation of three children’s graves, located in rural upstate New York and dating to 1979 and 1980, was warranted as their mother had come under suspicion for the death of a child she had been babysitting in late 2006. The local March weather conditions had been wet, and heavy rains fell during the 2‐day process of casket removal. The extremely wet soil and the poor preservation of two wooden caskets increased the likelihood of damage to evidence. After remains’ transport to the forensic center, an indoor wet‐screening station was established so that skeletal elements could be (i) separated from soil matrix and (ii) preserved carefully for analysis. Not only were the remains relatively small and fragile in comparison with those of an adult, but two of the three remains were known to be fire damaged, thus the use of special laboratory preparation techniques was crucial.     

Estimating the timing of long bone fractures: correlation between the postmortem interval, bone moisture content, and blunt force trauma fracture characteristics*

There is very limited knowledge about how long perimortem fracture characteristics persist into the postmortem interval (PMI). Therefore, in this study, 60 porcine long bones were exposed to natural taphonomic conditions and fractured with a steel bone breaking apparatus every 28 days throughout a 141-day period. Differences between macroscopic blunt force trauma fracture characteristics (fracture angle, surface morphology, and outline) were examined to determine if they varied over time or in relationship to bone moisture content (ash weight) and overall assessment. There are significant relationships between (1) PMI and percent ash weight (%AW), fracture surface, and fracture angle and (2) %AW and fracture surface and fracture angle. Bone moisture content correlates significantly with fracture morphology and other characteristics commonly used by forensic anthropologists to determine the timing of traumatic injuries. However, fracture characteristics normally associated with perimortem trauma can persist long into the PMI.     

Perimortem or Postmortem Bone Fractures? An Experimental Study of Fracture Patterns in Deer Femora*

The determination of perimortem trauma is important for forensic anthropologists. Characteristics of bone fractures such as sharp edges, presence of fracture lines, the shape of the broken ends, fracture surface morphology, fracture angle on the Z-axis, and butterfly fractures are said to differentiate perimortem from postmortem trauma. A Drop Weight Impact Test Machine was used to break 76 deer femora of various ages since death. The results of this study suggest that the characteristics listed above are unreliable at differentiating a perimortem fracture from a postmortem fracture in a forensic case. There are, however, statistically significant differences between fresh bones broken less than 4 days old and dry bones broken 44 days or 1 year old after death.     

Healing following cranial trauma

This paper reports on the gross appearance of the initial osseous response following cranial gunshot wounds. A total of 127 adult crania and cranial sections were analyzed for four types of bone response: osteoblastic, osteoclastic, line of demarcation, and sequestration. In general, no osteoblastic or osteoclastic response was noted during the first week. This response was followed by an increasing prevalence of expression after this time. By the sixth week postfracture both osteoclastic and osteoblastic activity was scored for 100% of the sample. Further, our observations suggest that the line of demarcation may establish the boundary between the living bone and bone not surviving the fracture. Sequestration appears to be a long-term event and was scored as present well past the eighth week of healing. The osseous expression of infection following fracture was also considered.     

Do bone elasticity and postmortem interval affect forensic fractographic analyses?

Forensic fractographic features of bone reliably establish crack propagation in perimortem injuries. We investigated if similar fracture surface features characterize postmortem fractures. Experimentally induced peri- and postmortem fractures were used to assess if fractographic features vary as bone elasticity decreases during the postmortem interval (PMI). Thirty-seven unembalmed, defleshed human femoral shafts from males and females aged 33–81 years were fractured at varying PMIs with a drop test frame using a three-point bending setup and recorded with a high-speed camera. Vital statistics, cause of death, PMI length, temperature, humidity, collagen percentage, water loss, fracture energy, and fractography scores were recorded for each sample. Results showed that fractographic features associated with perimortem fractures were expressed in PMIs up to 40,600 accumulated degree hours (ADH), or 60 warm weather days. Hackle was the most consistently expressed feature, occurring in all fractures regardless of ADH. The most variable characteristics were wake features (78.4%) and arrest ridges (70.3%). Collagen percentage did not correlate strongly with ADH (r = −0.04, p = 0.81); however, there was a strong significant correlation between ADH and water loss (r = 0.74, p < 0.001). Multinomial logistic regression showed no association between fractographic feature expression and ADH or collagen percentage. In conclusion, forensic fractographic features reliably determine initiation and directionality of crack propagation in experimentally induced PMIs up to 40,600 ADH, demonstrating the utility of this method into the recent postmortem interval. This expression of reliable fractographic features throughout the early PMI intimates these characteristics may not be useful standalone features for discerning peri- versus postmortem fractures.     

Primary and secondary skeletal blast trauma

This study examines primary (resulting from blast wave) and secondary (resulting from disintegrated, penetrating fragments) blast trauma to the skeleton. Eleven pigs were exposed to semi-controlled blast events of varying explosive type, charge size, and distance, including some cases with shrapnel. Skeletal trauma was found to be extensive, presenting as complex, comminuted fractures with numerous small, displaced bone splinters and fragments. Traumatic amputation of the limbs and cranium was also observed. Fractures were concentrated in areas nearer the blast, but there was generally no identifiable point of impact. Fractures were more random in appearance and widespread than those typically associated with gunshot or blunt force injury events. These patterns appear to be uniquely associated with blast trauma and may therefore assist forensic anthropologists and other forensic examiners in the interpretation of skeletal trauma by enabling them to differentiate between blast trauma and trauma resulting from some other cause.     

Discrimination of falls and blows in blunt head trauma: systematic study of the hat brim line rule in relation to skull fractures

In the discrimination of falls from blows in blunt head trauma, the hat brim line rule is one of the most often used criteria. The present study assesses the validity of the hat brim line rule for skull fractures and looks at other possible criteria. All autopsy cases were retrospectively analyzed on a 5-year period. Cases selected consisted of downstairs falls (n = 13), falls from one's own height (n = 23), and homicidal blows (n = 44). Results show that fractures above the hat brim line are more in favor of blows, while fractures in the hat brim line zone are more difficult to distinguish. The majority of fractures were located on the left side for homicidal blows and on the right side for falls. A higher average number of lacerations was revealed for homicidal blows. In conclusion, this study establishes three criteria in favor of blows: (i) localization of a wound above the hat brim line; (ii) left side lateralization; and (iii) a high number of lacerations.     

Applicability of Cranial Models in Urethane Resin and Foam as a Substitute for Bone: Are Synthetic Materials Reliable?

As literature is poor in functional synthetic cranial models, in this study, synthetic handmade models of cranial vaults were produced in two different materials (a urethane resin and a self‐hardening foam), from multiple bone specimens (eight original cranial vaults: four human and four swine), in order to test their resemblance to bone structure in behavior, during fracture formation. All the vaults were mechanically tested with a 2‐kg impact weight and filmed with a high‐speed camera. Fracture patterns were homogeneous in all swine vaults and heterogeneous in human vaults, with resin fractures more similar to bone fractures. Mean fracture latency time extrapolated by videos were of 0.75 msec (bone), 1.5 msec (resin), 5.12 msec (foam) for human vaults and of 0.625 msec (bone), 1.87 msec (resin), 3.75 msec (foam) for swine vaults. These data showed that resin models are more similar to bone than foam reproductions, but that synthetic material may behave quite differently from bone as concerns fracture latency times.     

Discrimination of Falls and Blows in Blunt Head Trauma: A Multi‐Criteria Approach

Abstract: In the discrimination of falls versus blows, the hat brim line (HBL) rule is mentioned in several textbooks as the most useful single criterion. Recent studies, however, have found that the HBL rule is only moderately valid and that its use on its own is not recommended. The purpose of this 6‐year retrospective study was to find additional individually useful criteria in the distinction of falls from blows. Overall, the following criteria were found to point toward blows: more than three lacerations, laceration length of 7 cm or more, comminuted or depressed calvarial fractures, lacerations or fractures located above the HBL, left‐side lateralization of lacerations or fractures, more than four facial contusions or lacerations, presence of ear lacerations, presence of facial fractures, and presence of postcranial osseous and/or visceral trauma. Based on the most discriminating criteria, a decision tree was constructed to be potentially applicable to future cases.     

Macroscopic Analysis of Axe and Hatchet Trauma in Fleshed and Defleshed Mammalian Long Bones*

Abstract: Recently, the authors have noted that many studies involving the characterization of chopping weapon wounds have used either semi‐fleshed or defleshed bones (e.g., J Forensic Sci 2001; 46: 228). As these types of specimens do not reflect the full range of actual cases of postmortem dismemberment or perimortem trauma, 11 fresh pig (Sus scrofa) articulated hind limbs, with contiguous surrounding flesh, were inflicted with wounds using two axes and two hatchets. Defleshed humeri and femora were subjected to the same treatment. While there were no great differences found between the fleshed and defleshed specimens, characteristics observed including entrance site width and the presence of chattering were inconsistent with some aspects of Humphrey and Hutchinson’s study (J Forensic Sci 2001; 46: 228). Further, it was found that curve transverse and spiral fractures were prevalent in femora, while longitudinal fractures were prevalent in fibulae. Hence, fracture types may play a role in characterizing some wounds caused by chopping weapons.     

Comparison of handmarks in manual strangulation: an experimental study

A police case with a strangulated woman with fingermarks on the neck and two suspects identifying each other as the perpetrator set off a laboratory experiment. Twenty-one males participated in the study. Blue paint was applied to their fingers, after which they grasped a neck dummy and pressed hard as if strangulating someone. The imprint was removed from the dummy, and their hands were photographed. Five imprints were randomly chosen and superimposed on the hand photographs in blind trials. In no cases did we match an imprint to the correct hand. However, in four cases we matched the imprint with several hands, one of which was the correct one. This means we were able to exclude nonmatches in 4/5 cases. Overall, matching of hands and fingermarks is difficult and inconclusive. Objective criteria for matching are difficult to establish, and matching is probably best suited for cases with specific anatomical features.